Stock-Based Compensation - Option Activity (Details) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) $ / shares shares
Number of Options (in 000's)
Outstanding at beginning of period (in shares) | shares	652
Granted (in shares) | shares	92
Exercised (in shares) | shares	(45)
Forfeited/canceled/expired (in shares) | shares	(168)
Outstanding at end of period (in shares) | shares	531
Vested and expected to vest at end of period (in shares) | shares	531
Exercisable at end of period (in shares) | shares	378
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 39.27
Granted (in dollars per share) | $ / shares	62.70
Exercised (in dollars per share) | $ / shares	24.87
Forfeited/canceled/expired (in dollars per share) | $ / shares	46.44
Outstanding at end of period (in dollars per share) | $ / shares	42.26
Vested and expected to vest at end of period (in dollars per share) | $ / shares	42.26
Exercisable at end of period (in dollars per share) | $ / shares	$ 35.35
Weighted-Average Remaining Contractual Term (in years)
Outstanding at end of period	4 years 5 months 26 days
Vested and expected to vest at end of period	4 years 5 months 26 days
Exercisable at end of period	3 years 11 months 8 days
Exercised | $	$ 1,893
Outstanding at end of period | $	11,391
Vested and expected to vest at end of period | $	11,390
Exercisable at end of period | $	$ 10,731