Shareholders' Equity Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	$ 520,745	$ 447,355
Net income (loss)	163,094	(38,697)
All other changes	556	380
As of ending balance	684,319	408,944
Share-based compensation	856	1,038
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	151	151
All other changes	1	0
As of ending balance	152	151
Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	200,666	197,630
All other changes	556	381
As of ending balance	201,222	198,011
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	319,987	249,492
Net income (loss)	163,094	(38,697)
All other changes	0	0
As of ending balance	483,005	210,701
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	(59)	82
All other changes	(1)	(1)
As of ending balance	$ (60)	$ 81
Time Vested Restricted Stock Units [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, Issued	22,321	24,657
Accounting Standards Update 2016-13 | Adjustment upon adoption
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	$ (76)
Accounting Standards Update 2016-13 | Adjustment upon adoption | Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance	$ (76)
Accounting Standards Update 2016-02 | Adjustment upon adoption
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance		$ (94)
Accounting Standards Update 2016-02 | Adjustment upon adoption | Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
As of beginning balance		$ (94)