Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
BALANCE at Dec. 31, 2018	$ 1,264,753	$ 805	$ 107,455	$ 1,413,746	$ (16,073)	$ (241,180)
Comprehensive income	36,599	0	0	36,086	513	0
Purchases of common stock	(20,545)	0	0	0	0	(20,545)
Dividends on common stock	(6,290)	0	0	(6,290)	0	0
Equity compensation activity	(1,179)	0	(1,578)	0	0	399
Non-cash equity compensation expense	2,051	0	2,051	0	0	0
BALANCE at Mar. 31, 2019	1,275,389	805	107,928	1,443,542	(15,560)	(261,326)
BALANCE at Dec. 31, 2019	1,111,008	805	112,649	1,294,608	(14,728)	(282,326)
Comprehensive income	7,568	0	0	23,058	(15,490)	0
Purchases of common stock	(8,798)	0	0	0	0	(8,798)
Dividends on common stock	(6,218)	0	0	(6,218)	0	0
Equity compensation activity	(3,930)	0	(4,360)	0	0	430
Non-cash equity compensation expense	2,406	0	2,406	0	0	0
BALANCE at Mar. 31, 2020	$ 1,102,036	$ 805	$ 110,695	$ 1,311,448	$ (30,218)	$ (290,694)