Stock-Based Compensation - RSU Activity (Details) - 2012 Plan - RSUs shares in Thousands	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Number of shares outstanding
Balance at the beginning of the period ( in shares) | shares	1,318
Granted (in shares) | shares	239
Vested/Released (in shares) | shares	(156)
Forfeited (in shares) | shares	(90)
Balance at the end of the period ( in shares) | shares	1,311
Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share) | $ / shares	$ 20.89
Grant date fair value (in dollars per share) | $ / shares	22.38
Vested/Released (in dollars per share) | $ / shares	19.28
Forfeited (in dollars per share) | $ / shares	19.63
Balance at the end of the period (in dollars per share) | $ / shares	$ 21.44