CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjusted Balance	Series F Preferred Stock	Series A Preferred Stock	Class C non-voting common stock	Series D Preferred Stock	Series B Preferred Stock	Preferred Stock	Preferred Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Preferred Stock Series E Preferred Stock	Preferred Stock Series F Preferred Stock	Preferred Stock Series A Preferred Stock	Preferred Stock Series D Preferred Stock	Preferred Stock Series B Preferred Stock	Common Stock	Common Stock Cumulative Effect, Period of Adoption, Adjusted Balance	Common Stock Class C non-voting common stock	Additional Paid-in Capital	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjusted Balance	Additional Paid-in Capital Class C non-voting common stock	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings Cumulative Effect, Period of Adoption, Adjusted Balance	Retained Earnings Class C non-voting common stock
Beginning balance ( in shares) at Dec. 31, 2018									8,400							10,669
Beginning Balance at Dec. 31, 2018	$ 752,557								$ 204,759							$ 10,669			$ 118,822			$ 24,956		$ 393,351
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	25,170																							25,170
Other comprehensive income, net of tax	(3,702)																					(3,702)
Cash dividends, preferred stock	(3,296)																							(3,296)
Cash dividends, common stock	(7,470)																							(7,470)
Issuance of stock (in shares)																		20
Issuance of stock						$ 23												$ 20			$ 3
Stock-based compensation cost	724																		724
Other stock-based award activity	(708)																		(708)
Ending balance (in shares) at Mar. 31, 2019									8,400							10,689
Ending balance at Mar. 31, 2019	763,298								$ 204,759							$ 10,689			118,841			21,254		407,755
Beginning balance ( in shares) at Dec. 31, 2018									8,400							10,669
Beginning Balance at Dec. 31, 2018	752,557								$ 204,759							$ 10,669			118,822			24,956		393,351
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	77,048
Other comprehensive income, net of tax	(67,980)
Loss on retirement of preferred stock	(1,956)
Ending balance (in shares) at Sep. 30, 2019									9,400							10,710
Ending balance at Sep. 30, 2019	750,259								$ 228,374							$ 10,710			118,720			(43,024)		435,479
Beginning balance ( in shares) at Mar. 31, 2019									8,400							10,689
Beginning Balance at Mar. 31, 2019	763,298								$ 204,759							$ 10,689			118,841			21,254		407,755
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	34,045																							34,045
Other comprehensive income, net of tax	(34,097)																					(34,097)
Cash dividends, preferred stock	(3,785)																							(3,785)
Cash dividends, common stock	(7,490)																							(7,490)
Issuance of stock (in shares)														4,000				11
Issuance of stock						14	$ 96,659							$ 96,659				$ 11			3
Redemption of preferred stock (in shares)															(3,000)
Redemption of preferred stock								$ (73,044)							$ (73,044)
Loss on retirement of preferred stock	(1,956)																							(1,956)
Stock-based compensation cost	533																		533
Other stock-based award activity	(435)																		(435)
Ending balance (in shares) at Jun. 30, 2019									9,400							10,700
Ending balance at Jun. 30, 2019	773,742								$ 228,374							$ 10,700			118,942			(12,843)		428,569
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	17,833																							17,833
Other comprehensive income, net of tax	(30,181)																					(30,181)
Cash dividends, preferred stock	(3,427)																							(3,427)
Cash dividends, common stock	(7,496)																							(7,496)
Issuance of stock (in shares)																		10
Issuance of stock						29												$ 10			19
Loss on retirement of preferred stock	0
Stock-based compensation cost	407																		407
Other stock-based award activity	(648)																		(648)
Ending balance (in shares) at Sep. 30, 2019									9,400							10,710
Ending balance at Sep. 30, 2019	750,259								$ 228,374							$ 10,710			118,720			(43,024)		435,479
Beginning balance ( in shares) at Dec. 31, 2019									9,400	9,400						10,712	10,712
Beginning Balance at Dec. 31, 2019	799,276	$ (2,099)	$ 797,177						$ 228,374	$ 228,374						$ 10,712	$ 10,712		119,304	$ 119,304		(16,161)	$ (16,161)	457,047	$ (2,099)	$ 454,948
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,830																							12,830
Other comprehensive income, net of tax	(105,276)																					(105,276)
Cash dividends, preferred stock	(3,431)																							(3,431)
Cash dividends, common stock	(8,571)																							(8,571)
Issuance of stock (in shares)																		15
Issuance of stock						34												$ 15			19
Repurchase of Class C Common Stock (in shares)																		(4)
Repurchase of Class C Common Stock						(235)												$ (4)									$ (231)
Stock-based compensation cost	1,293																		1,293
Other stock-based award activity	(204)																		(204)
Ending balance (in shares) at Mar. 31, 2020									9,400							10,723
Ending balance at Mar. 31, 2020	693,617								$ 228,374							$ 10,723			120,412			(121,437)		455,545
Beginning balance ( in shares) at Dec. 31, 2019									9,400	9,400						10,712	10,712
Beginning Balance at Dec. 31, 2019	799,276	$ (2,099)	$ 797,177						$ 228,374	$ 228,374						$ 10,712	$ 10,712		119,304	$ 119,304		(16,161)	$ (16,161)	457,047	$ (2,099)	$ 454,948
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	73,948
Other comprehensive income, net of tax	(37,676)
Loss on retirement of preferred stock	(1,667)
Ending balance (in shares) at Sep. 30, 2020									14,980							10,736
Ending balance at Sep. 30, 2020	930,345								$ 363,204							$ 10,736			121,525			(53,837)		488,717
Beginning balance ( in shares) at Mar. 31, 2020									9,400							10,723
Beginning Balance at Mar. 31, 2020	693,617								$ 228,374							$ 10,723			120,412			(121,437)		455,545
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	35,626																							35,626
Other comprehensive income, net of tax	29,940																					29,940
Cash dividends, preferred stock	(3,939)																							(3,939)
Cash dividends, common stock	(8,585)																							(8,585)
Issuance of stock (in shares)											3,180							10
Issuance of stock	77,003					27					$ 77,003							$ 10			17
Stock-based compensation cost	719																		719
Other stock-based award activity	(292)																		(292)
Ending balance (in shares) at Jun. 30, 2020									12,580							10,733
Ending balance at Jun. 30, 2020	824,116								$ 305,377							$ 10,733			120,856			(91,497)		478,647
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	25,492																							25,492
Other comprehensive income, net of tax	37,660																					37,660
Cash dividends, preferred stock	(5,166)																							(5,166)
Cash dividends, common stock	(8,589)																							(8,589)
Issuance of stock (in shares)												4,800						3
Issuance of stock				$ 116,160		$ 11						$ 116,160						$ 3			$ 8
Redemption of preferred stock (in shares)													(2,400)
Redemption of preferred stock					$ (58,333)								$ (58,333)
Loss on retirement of preferred stock	(1,667)																							(1,667)
Stock-based compensation cost	753																		753
Other stock-based award activity	(92)																		(92)
Ending balance (in shares) at Sep. 30, 2020									14,980							10,736
Ending balance at Sep. 30, 2020	$ 930,345								$ 363,204							$ 10,736			$ 121,525			$ (53,837)		$ 488,717