Annual report pursuant to Section 13 and 15(d)

Share-Based and Cash-Based Incentive Compensation - Additional Information (Details)

v3.3.1.900
Share-Based and Cash-Based Incentive Compensation - Additional Information (Details) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Additional shares authorized under share based compensation arrangements     4,000,000    
Common stock available for award under plans     4,239,548    
Restricted Shares          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Shares granted, grant date fair value     $ 0.3 $ 0.3 $ 0.3
Shares vested, vested date fair value     $ 0.1 $ 0.3 $ 0.4
Number of shares granted     56,540 18,815 27,450
Unrecognized share-based compensation expense     $ 0.5    
Recognition period for unrecognized compensation expense     2018-04    
Restricted Stock Units (RSUs)          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Shares granted, grant date fair value     $ 9.4 $ 20.1 $ 12.8
Shares vested, vested date fair value     $ 2.1 $ 2.0 $ 7.2
Adjusted EBITDA         40.00%
Adjusted EBITDA margin         30.00%
TSR ranking         30.00%
TSR ranking for each of three-year performance periods         10.00%
Expected volatility, minimum         30.00%
Expected volatility, maximum         63.00%
Number of shares granted     2,626,930 1,195,388 969,919
Unrecognized share-based compensation expense     $ 12.7    
Recognition period for unrecognized compensation expense     2017-11    
Restricted Stock Units (RSUs) | London Interbank Offered Rate (LIBOR)          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Risk-free interest rate, minimum         0.27%
Risk-free interest rate, maximum         0.91%
Restricted Stock Units (RSUs) | Minimum          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Expected dividend yield         0.00%
Correlation of movement of total shareholder return         (84.00%)
Restricted Stock Units (RSUs) | Maximum          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Expected dividend yield         3.10%
Correlation of movement of total shareholder return         95.00%
CEO's 2014 Award | Chief Executive Officer          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Number of shares issued 37,316        
CEO's 2013 Award | Chief Executive Officer          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Number of shares issued   42,547      
Number of shares granted   42,547      
Directors Compensation Plan          
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Common stock available for award under plans     444,024