Stock-based Compensation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Shares
Outstanding at beginning of period	4,748
Granted	831
Exercised	(456)
Forfeited	(14)
Outstanding at end of period	5,109	4,748
Exercisable at end of period	3,849
Vested and expected to vest at end of period	5,046
Weighted-Average Exercise Price
Outstanding at beginning of period	$ 27.49
Granted	30.75
Exercised	17.65
Forfeited	31.91
Outstanding at end of period	28.88	$ 27.49
Exercisable at end of period	28.16
Vested and expected to vest at end of period	$ 28.86
Weighted-Average Remaining Contractual Term (in years)
Outstanding at beginning of period	5 years 7 months	5 years 6 months
Exercisable at end of period	4 years 7 months
Vested and expected to vest at end of period	5 years 7 months
Outstanding at end of period	5 years 7 months	5 years 6 months
Aggregate Intrinsic Value
Outstanding at end of period	$ 37,324
Exercisable at end of period	30,916
Vested and expected to vest at end of period	$ 37,004