Investment Securities - Age of Unrealized Losses and Fair Value of Related Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value
Less than Twelve Months	$ 1,893,052	$ 1,440,435
More than Twelve Months	570,776	242,949
Total	2,463,828	1,683,384
Unrealized Losses
Less than Twelve Months	(108,672)	(22,830)
More than Twelve Months	(55,910)	(11,242)
Total	(164,582)	(34,072)
U.S. government agency securities
Fair Value
Less than Twelve Months	4,092
More than Twelve Months	0
Total	4,092
Unrealized Losses
Less than Twelve Months	(119)
More than Twelve Months	0
Total	(119)	0
Obligations of states and state agencies
Fair Value
Less than Twelve Months	38,979	17,000
More than Twelve Months	5,317	5,517
Total	44,296	22,517
Unrealized Losses
Less than Twelve Months	(815)	(254)
More than Twelve Months	(239)	(58)
Total	(1,054)	(312)
Municipal bonds
Fair Value
Less than Twelve Months	25,255	9,403
More than Twelve Months	1,305	0
Total	26,560	9,403
Unrealized Losses
Less than Twelve Months	(1,514)	(87)
More than Twelve Months	(90)	0
Total	(1,604)	(87)
Obligations of states and political subdivisions
Fair Value
Less than Twelve Months	64,234	26,403
More than Twelve Months	6,622	5,517
Total	70,856	31,920
Unrealized Losses
Less than Twelve Months	(2,329)	(341)
More than Twelve Months	(329)	(58)
Total	(2,658)	(399)
Residential mortgage-backed securities
Fair Value
Less than Twelve Months	1,786,943	1,381,405
More than Twelve Months	533,425	206,520
Total	2,320,368	1,587,925
Unrealized Losses
Less than Twelve Months	(105,507)	(22,365)
More than Twelve Months	(50,283)	(6,075)
Total	(155,790)	(28,440)
Trust preferred securities
Fair Value
Less than Twelve Months	0	0
More than Twelve Months	30,729	30,912
Total	30,729	30,912
Unrealized Losses
Less than Twelve Months	0	0
More than Twelve Months	(5,298)	(5,109)
Total	(5,298)	(5,109)
Corporate and other debt securities
Fair Value
Less than Twelve Months	37,783	32,627
More than Twelve Months	0	0
Total	37,783	32,627
Unrealized Losses
Less than Twelve Months	(717)	(124)
More than Twelve Months	0	0
Total	$ (717)	$ (124)

Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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