Net Income per Share - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net income	$ 22,328	$ 31,643
Less: Net income allocated to unvested participating restricted stock	(748)	(1,111)
Net income available to common stockholders - basic	21,580	30,532
Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units	4	12
Net income available to common stockholders - diluted	$ 21,584	$ 30,544
Weighted average outstanding shares of common stock - basic (in shares)	16,263	17,343
Dilutive effect of stock options (in shares)	207	347
Weighted average outstanding shares of common stock - diluted (in shares)	16,470	17,690
Net income per common share - basic (USD per share)	$ 1.33	$ 1.76
Net income per common share - diluted (USD per share)	$ 1.31	$ 1.73