CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Treasury Shares [Member]		Treasury Shares [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Common Stock [Member]	Common Stock [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Preferred Shares Issued [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period Of Adoption, Adjustment [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Cumulative Effect, Period Of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle (ASU 2016-13)	$ 501,633			$ (130,399)			$ 465			$ 86,353		$ 553,224			$ (8,010)
Beginning balance at Dec. 31, 2018	501,633			$ (130,399)			$ 465			86,353		553,224			(8,010)
Beginning balance (in shares) at Dec. 31, 2018				(11,731)			(46,514)		(10)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle (ASU 2016-13)	539,050			$ (140,516)			$ 467			87,328		587,797			3,974
Vesting of performance share units	(2,069)			$ (2,069)			$ 2			(2)
Vesting of performance share units (in shares)				56	[1]		148
Grants and vesting of restricted stock	(166)			$ (166)
Grants and vesting of restricted stock (in shares)				5	[1]		25
Stock option exercises	72			$ (1,367)			$ 1			1,438
Stock option exercises (in shares)				36	[1]		84
Retirement of treasury shares	0			$ 3,602			$ (1)			(3,601)
Retirement of treasury shares, shares (in shares)				(97)	[1]		(97)
Purchases of treasury stock	(10,117)			$ (10,117)
Purchases of treasury stock (in shares)				(321)
Share-based compensation	3,140									3,140
Net income	40,148											40,148
Other comprehensive income (loss)	11,984														11,984
Declaration of dividends	(5,575)											(5,575)
Ending balance at Mar. 31, 2019	539,050			$ (140,516)			$ 467			87,328		587,797			3,974
Ending balance (in shares) at Mar. 31, 2019				(12,052)			(46,674)		(10)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle (ASU 2016-13)	539,050			$ (140,516)			$ 467			87,328		587,797			3,974
Cumulative effect of changes in accounting principle (ASU 2016-13)	493,901	$ 0	$ 493,901	(196,585)		$ (196,585)	467	$ 467		96,036	$ 96,036	573,619	$ (597)	$ 573,022	20,364	$ 597	$ 20,961
Beginning balance at Dec. 31, 2019	493,901	0	493,901	$ (196,585)		(196,585)	$ 467	467		96,036	96,036	573,619	(597)	573,022	20,364	597	20,961
Beginning balance (in shares) at Dec. 31, 2019				(14,069)			(46,707)		(10)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle (ASU 2016-13)	494,288	$ 0	$ 493,901	$ (203,172)		$ (196,585)	$ 468	$ 467		97,110	$ 96,036	587,867	$ (597)	$ 573,022	12,015	$ 597	$ 20,961
Vesting of performance share units	(646)			$ (646)			$ 1			(1)
Vesting of performance share units (in shares)				25	[1]		83
Grant and issue of stock award	30									30
Grant and issue of stock award (in shares)							1
Retirement of treasury shares	0			$ 646						(646)
Retirement of treasury shares, shares (in shares)				(25)			(25)
Purchases of treasury stock	(6,587)			$ (6,587)
Purchases of treasury stock (in shares)				(312)
Share-based compensation	1,691									1,691
Net income	20,067											20,067
Other comprehensive income (loss)	(8,946)														(8,946)
Declaration of dividends	(5,222)											(5,222)
Ending balance at Mar. 31, 2020	494,288			$ (203,172)			$ 468			97,110		587,867			12,015
Ending balance (in shares) at Mar. 31, 2020				(14,381)			(46,766)		(10)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of changes in accounting principle (ASU 2016-13)	$ 494,288			$ (203,172)			$ 468			$ 97,110		$ 587,867			$ 12,015

[1] All shares acquired represent shares tendered to cover the strike price for options and tax withholdings on the intrinsic value of stock options exercised, restricted stock vested, performance share units vested or restricted stock units vested. These shares have been cancelled by the Company.