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Stock-based Compensation - Restricted Stock Units (RSUs) Activity (Details) - Restricted stock units
12 Months Ended
Dec. 31, 2020
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]  
Non-vested at December 31, 2015 (in shares) | shares 1,435,774
Granted (in shares) | shares 824,827
Vested (in shares) | shares (455,278)
Forfeited (in shares) | shares (200,601)
Non-vested at December 31, 2016 (in shares) | shares 1,604,722
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]  
Non-vested at December 31, 2015 (in dollars per share) | $ / shares $ 18.69
Granted (in dollars per share) | $ / shares 29.15
Vested (in dollars per share) | $ / shares 15.29
Forfeited (in dollars per share) | $ / shares 21.98
Non-vested at December 31, 2016 (in dollars per share) | $ / shares $ 24.61