Consolidated Statements Of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balances, shares at Dec. 31, 2017	49,143	49,143
Balances, value at Dec. 31, 2017	$ 1,339,138	$ 4,914	$ 634,192	$ 708,181	$ (8,149)
Stock-based compensation expense	$ 2,870	$ 0	2,870	0	0
Shares repurchased and retired, shares	(1,911)	(1,911)
Shares repurchased and retired, value	$ (68,381)	$ (191)	(31,252)	(36,938)	0
Stock options exercised, shares	168	168
Stock options exercised, value	$ 3,079	$ 17	3,062	0	0
Vesting of restricted stock units, shares	198	198
Vesting of restricted stock units, value	$ 0	$ 20	(20)	0	0
Shares withheld for taxes, shares	(26)	(26)
Shares withheld for taxes, value	$ (763)	$ (3)	(760)	0	0
Dividends declared	(7,136)	0	0	(7,136)	0
Net income (loss)	(23,641)	0	0	(23,641)	0
Other comprehensive income (loss)	$ 2,165	$ 0	0	0	2,165
Balances, shares at Mar. 31, 2018	47,572	47,572
Balances, value at Mar. 31, 2018	$ 1,247,331	$ 4,757	608,092	640,466	(5,984)
Balances, shares at Dec. 31, 2018	41,357	41,357
Balances, value at Dec. 31, 2018	$ 1,132,225	$ 4,136	554,939	584,274	(11,124)
Stock-based compensation expense	$ 2,772	$ 0	2,772	0	0
Shares repurchased and retired, shares	(2,383)	(2,383)
Shares repurchased and retired, value	$ (61,080)	$ (239)	(26,473)	(34,368)	0
Stock options exercised, shares	13	13
Stock options exercised, value	$ 279	$ 1	278	0	0
Vesting of restricted stock units, shares	227	227
Vesting of restricted stock units, value	$ 0	$ 23	(23)	0	0
Shares withheld for taxes, shares	(45)	(45)
Shares withheld for taxes, value	$ (1,236)	$ (4)	(1,232)	0	0
Dividends declared	(5,875)	0	0	(5,875)	0
Net income (loss)	13,773	0	0	13,773	0
Other comprehensive income (loss)	$ (2,133)	$ 0	0	0	(2,133)
Balances, shares at Mar. 31, 2019	39,169	39,169
Balances, value at Mar. 31, 2019	$ 1,078,725	$ 3,917	$ 530,261	$ 557,804	$ (13,257)