Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
		Sep. 11, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 10, 2018
Numerator for Earnings per Share Basic and Diluted:
Net income			$ 26,936	$ 30,881	$ 75,965	$ 78,480
Less: Income allocated to participating shares			72	87	204	229
Net Income Allocated to Shareholders			26,864	30,794	75,761	78,251
Net Income Available to Shareholders			$ 26,936	$ 30,881	$ 75,965	$ 78,480
Denominators for Earnings per Share:
Weighted Average Shares Outstanding—Basic (in shares)			34,090,779	34,799,174	34,221,479	34,783,175
Add: Potentially dilutive shares (in shares)			79,502	220,118	105,746	228,909
Denominator for Treasury Stock Method—Diluted (in shares)			34,170,281	35,019,292	34,327,225	35,012,084
Weighted Average Shares Outstanding—Basic (in shares)			34,090,779	34,799,174	34,221,479	34,783,175
Add: Average participating shares outstanding (in shares)			186,491	98,579	186,253	101,808
Denominator for Two-Class Method—Diluted (in shares)			34,277,270	34,897,753	34,407,732	34,884,983
Earnings per share—basic (in dollars per share)			$ 0.79	$ 0.89	$ 2.22	$ 2.26
Earnings per share—diluted (in dollars per share)			$ 0.79	0.88	$ 2.21	$ 2.24
Repurchase of warrant		$ 7,700			$ 0	$ 7,652
Number of shares of common stock that holder of warrants have right to purchase (in shares)							517,012
Anti-dilutive warrants - exercise price (in dollars per share)				$ 31.53		$ 31.53	$ 31.53
Warrants
Denominators for Earnings per Share:
Anti-dilutive excluded from potentially dilutive shares (in shares)	[1]		0	285,915	0	351,166
Restricted Stock
Denominators for Earnings per Share:
Anti-dilutive excluded from potentially dilutive shares (in shares)			254	113,451	360	113,390

[1] We repurchased our outstanding warrant on September 11, 2018 for $7.7 million. Prior to the repurchase, the warrant provided the holder the right to 517,012 shares of common stock at a strike price of $31.53 per share via cashless exercise.