Stock Options, Restricted Stock Units and Employee Stock Purchase Plan - Non-vested Restricted Stock Activity (Details) - Restricted stock units shares in Thousands	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Number of Units
Non-vested shares, beginning balance (in Shares) | shares	416
Granted (in Shares) | shares	662
Vested (in Shares) | shares	(14)
Forfeited (in Shares) | shares	(25)
Non-vested shares, ending balance (in Shares) | shares	1,039
Weighted Average Per Share Grant Date Fair Value
Weighted average grant date fair value, beginning balance (in Dollars per share) | $ / shares	$ 31.52
Granted (in Dollars per share) | $ / shares	33.10
Vested (in Dollars per share) | $ / shares	24.74
Forfeited (in Dollars per share) | $ / shares	30.62
Weighted average grant date fair value, ending balance (in Dollars per share) | $ / shares	$ 30.75