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Stock-Based Compensation - Valuation Assumptions (Details) - $ / shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Weighted average fair value of grants $ 24.47 $ 13.64 $ 9.26
Risk-free interest rate 1.39% 1.29% 0.95%
Expected volatility 43.36% 44.84% 53.39%
Expected life in years 4 years 6 months 25 days 4 years 6 months 21 days 5 years 2 months 12 days