Stock Incentive Plans - Summary of Restricted Stock Activity (Details) - Restricted Stock $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($) $ / shares shares
Number of Restricted Stock
Outstanding, as of beginning of period (in shares) | shares	1,355
Granted (in shares) | shares	125
Forfeited (in shares) | shares	(27)
Vested (in shares) | shares	(56)
Outstanding, as of end of period (in shares) | shares	1,397
Weighted Average Grant Date Fair Value
Outstanding, as of beginning of period (in dollars per share) | $ / shares	$ 22.67
Granted (in dollars per share) | $ / shares	27.24
Forfeited (in dollars per share) | $ / shares	20.81
Vested (in dollars per share) | $ / shares	24.81
Outstanding, as of end of period (in dollars per share) | $ / shares	$ 23.15
Vested, total intrinsic value of restricted stock vested | $	$ 1,564