STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock [Member]	Retained Earnings	Accumulated OCI
Balance at Dec. 31, 2015	$ 1,054,208	$ 750	$ 879,578		$ 166,840	$ 7,040
Equity-based compensation cost	87		87
Net income	65,774				65,774
Other comprehensive income (loss)	(39,571)					(39,571)
Balance at Dec. 31, 2016	1,080,498	750	879,665		232,614	(32,531)
Equity-based compensation cost	1,880		1,880
Net income	102,353				102,353
Other comprehensive income (loss)	18,744					18,744
Reclassification of amounts within AOCI to retained earnings due to tax reform					5,246	(5,246)
Issuance of 8,625,000 common shares,net of issuance costs	155,581	86	155,495
Balance at Dec. 31, 2017	1,359,056	836	1,037,040		340,213	(19,033)
Equity-based compensation cost	3,960		3,960
Net income	166,261				166,261
Cash dividends declared ($0.55 per common share)	(45,995)				(45,995)
Dividend equivalents on restricted stock (Note 22)	(119)				(119)
Cumulative effect of adoption of new accounting principles (Note 1)	1,000				1,000
Purchase of treasury stock - at cost	(22,010)			$ (22,010)
Other comprehensive income (loss)	(23,879)					(23,879)
Balance at Dec. 31, 2018	$ 1,438,274	$ 836	$ 1,041,000	$ (22,010)	$ 461,360	$ (42,912)