Stock-Based Compensation - Summary of Restricted Stock Units and Restricted Stock (Details) - Restricted stock and restricted stock units	3 Months Ended
	Mar. 31, 2019 $ / shares shares
Number
Beginning balance (in shares) | shares	241,000
Granted (in shares) | shares	194,000
Vested (in shares) | shares	(60,000)
Forfeited (in shares) | shares	(1,000)
Ending balance (in shares) | shares	374,000
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) | $ / shares	$ 45.47
Granted (in dollars per share) | $ / shares	40.49
Vested (in dollars per share) | $ / shares	42.91
Forfeited (in dollars per share) | $ / shares	52.06
Ending balance (in dollars per share) | $ / shares	$ 43.29