Earnings Per Share - Reconciliation of Numerators and Denominators of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								12 Months Ended
	Sep. 11, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Sep. 10, 2018
Numerator for Earnings per Common Share-Basic:
Net Income		$ 24,176	$ 16,705	$ (33,072)	$ 13,231	$ 22,269	$ 26,936	$ 26,101	$ 22,929	$ 21,040	$ 98,234	$ 105,334
Less: Income allocated to participating shares										68	260	304
Net Income Allocated to Common Shareholders										20,972	97,974	105,030
Numerator for Earnings per Common Share—Diluted:
Net Income		$ 24,176	$ 16,705	$ (33,072)	$ 13,231	$ 22,269	$ 26,936	$ 26,101	$ 22,929	$ 21,040	$ 98,234	$ 105,334
Denominators:
Weighted Average Common Shares Outstanding-Basic (in shares)										39,070,439	34,628,191	34,775,784
Add: Dilutive potential common shares (in shares)										43,193	94,763	199,625
Denominator for Treasury Stock Method-Diluted (in shares)										39,113,632	34,722,954	34,975,409
Weighted Average Common Shares Outstanding-Basic (in shares)										39,070,439	34,628,191	34,775,784
Add: Average participating shares outstanding (in shares)										2,780	51,287	100,733
Denominator for Two-Class Method-Diluted (in shares)										39,073,219	34,679,478	34,876,517
Earnings per common share—basic (in USD per share)										$ 0.54	$ 2.84	$ 3.03
Earnings per common share—diluted (in USD per share)		$ 0.62	$ 0.43	$ (0.85)	$ 0.34	$ 0.62	$ 0.79	$ 0.76	$ 0.66	$ 0.53	$ 2.82	$ 3.01
Repurchase of warrant	$ 7,700									$ 0	$ 0	$ 7,652
Number of shares of common stock that holder of warrants have right to purchase (in shares)													517,012
Warrants exercise price (in USD per share)		$ 31.53				$ 31.53				$ 31.53	$ 31.53	$ 31.53	$ 31.53
Warrants
Denominators:
Anti-dilutive securities excluded from dilutive potential common shares										0	0	267,106
Restricted Stock
Denominators:
Anti-dilutive securities excluded from dilutive potential common shares										1,242	12,686	81,587