CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]	Total
Balances at Dec. 31, 2016		$ 2	$ 141,058	$ (8,132)	$ 324,576	$ 457,504
Balances, Shares at Dec. 31, 2016		19,057
Net income					72,060	72,060
Adoption of ASU 2016-09					1,004	1,004
Foreign currency translation adjustment				2,010		2,010
Issuance of common and preferred stock, net of offering costs			29,148			29,148
Issuance of common and preferred stock, net of offering costs, Shares		889
Exercise of stock options			145			145
Exercise of stock options, Shares		414
Stock-based compensation			1,974			1,974
Stock-based compensation, Shares		31
Balances at Dec. 31, 2017		$ 2	172,325	(6,122)	397,640	563,845
Balances, Shares at Dec. 31, 2017		20,391
Net income					78,596	78,596
Preferred stock dividends, $2.125/share					(5,124)	(5,124)
Foreign currency translation adjustment				(391)		(391)
Issuance of common and preferred stock, net of offering costs	$ 103,865					102,313
Issuance of common and preferred stock, net of offering costs			(1,552)
Issuance of common and preferred stock, net of offering costs, Shares	4,155	100
Repurchase of common stock			(40,869)			(40,869)
Repurchase of common stock, Shares		(1,767)
Exercise of stock options			24			24
Exercise of stock options, Shares		5
Stock-based compensation			2,738			2,738
Stock-based compensation, Shares		35
Balances at Dec. 31, 2018	$ 103,865	$ 2	132,666	(6,513)	471,112	701,132
Balances, Shares at Dec. 31, 2018	4,155	18,764
Net income					31,011	31,011
Preferred stock dividends, $2.125/share					(8,829)	(8,829)
Foreign currency translation adjustment				(117)		(117)
Repurchase of common stock		$ (1,458)	(34,118)			$ (34,118)
Repurchase of common stock, Shares						(1,500)
Exercise of stock options			1,285			$ 1,285
Exercise of stock options, Shares		130
Stock-based compensation			2,876			2,876
Stock-based compensation, Shares		43
Balances at Dec. 31, 2019	$ 103,865	$ 2	$ 102,709	$ (6,630)	$ 493,294	$ 693,240
Balances, Shares at Dec. 31, 2019	4,155	17,479