Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Fair Value of SAR's Using Black-Scholes Option-Pricing Model (Details)

v3.7.0.1
Stock-Based Compensation - Fair Value of SAR's Using Black-Scholes Option-Pricing Model (Details) - Black Scholes - Stock appreciation rights - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Estimated fair value of SAR grant using Black-Scholes options pricing model      
Dividend yield 0.00% 0.00% 0.00%
Weighted average risk-free interest rate, Minimum 1.10% 1.40% 1.50%
Weighted average risk-free interest rate, Maximum 1.40% 1.60% 1.80%
Weighted average expected volatility 40.00% 40.00% 40.00%
Expected life in years 6 years 3 months 6 years 3 months 6 years 3 months
Minimum      
Estimated fair value of SAR grant using Black-Scholes options pricing model      
The weighted average fair value of stock appreciation rights issued (in dollars per share) $ 2.79 $ 3.33 $ 4.18
Maximum      
Estimated fair value of SAR grant using Black-Scholes options pricing model      
The weighted average fair value of stock appreciation rights issued (in dollars per share) $ 3.74 $ 3.90 $ 4.93