Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Sep. 11, 2018	Mar. 31, 2019	Mar. 31, 2018		Sep. 10, 2018
Numerator for Earnings per Share Basic and Diluted:
Net income		$ 22,928	$ 26,163
Less: Income allocated to participating shares		62	80
Net Income Allocated to Shareholders		22,866	26,083
Net Income Available to Shareholders		$ 22,928	$ 26,163
Denominators for Earnings per Share:
Weighted Average Shares Outstanding—Basic (in shares)		34,414,555	34,756,726
Add: Potentially dilutive shares (in shares)		128,256	242,439
Denominator for Treasury Stock Method—Diluted (in shares)		34,542,811	34,999,165
Weighted Average Shares Outstanding—Basic (in shares)		34,414,555	34,756,726
Add: Average participating shares outstanding (in shares)		92,659	106,722
Denominator for Two-Class Method—Diluted (in shares)		34,507,214	34,863,448
Earnings per share—basic (in dollars per share)		$ 0.67	$ 0.75
Earnings per share—diluted (in dollars per share)		0.66	0.75
Repurchase of warrant	$ 7,700
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)		0	400,722	[1]
Restricted Stock
Denominators for Earnings per Share:
Anti-dilutive excluded from potentially dilutive shares (in shares)		68,314	90,298

[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.