CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common shares par value [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Accumulated other comprehensive loss [Member]
Balance, beginning of year at Dec. 31, 2018	$ 915,413	$ 44,647	$ 0	$ 927,345	$ (56,579)
Balance (in shares) at Dec. 31, 2018	44,647
Net (loss) income	$ 41,190			41,190
Cash dividends (quarters ended March 31, 2020 and 2019 - $0.30 per share)	(13,170)			(13,170)
Common shares issued	$ 1,948	86	1,862
Common shares issued (in shares)	86
Common shares repurchased	$ (50,000)	(1,038)	(2,478)	(46,484)
Common shares repurchased (in shares)	(1,038)
Other common shares retired	$ (2,672)	(57)	(2,615)
Other common shares retired (in shares)	(57)
Employee share-based compensation	$ 3,231		3,231
Other comprehensive (loss) income	1,890				1,890
Balance, end of period at Mar. 31, 2019	$ 897,563	43,638	0	908,614	(54,689)
Balance (in shares) at Mar. 31, 2019	43,638
Adoption of new accounting pronouncement | Adoption of Accounting Standards Update No. 2016-02 [Member]	$ (267)			(267)
Balance, beginning of year at Dec. 31, 2019	$ 570,861	42,126	4,086	572,596	(47,947)
Balance (in shares) at Dec. 31, 2019	42,126
Net (loss) income	$ (60,131)			(60,131)
Cash dividends (quarters ended March 31, 2020 and 2019 - $0.30 per share)	(12,861)			(12,861)
Common shares issued	$ 1,882	81	1,801
Common shares issued (in shares)	81
Common shares repurchased	$ (14,000)	(499)	(9,767)	(3,734)
Common shares repurchased (in shares)	(499)
Other common shares retired	$ (796)	(17)	(779)
Other common shares retired (in shares)	(17)
Employee share-based compensation	$ 4,659		4,659
Other comprehensive (loss) income	(12,007)				(12,007)
Balance, end of period at Mar. 31, 2020	$ 473,967	$ 41,691	$ 0	$ 492,230	$ (59,954)
Balance (in shares) at Mar. 31, 2020	41,691
Adoption of new accounting pronouncement | Adoption of Accounting Standards Update No. 2016-13 [Member]	$ (3,640)