Investment Securities - Age of Unrealized Losses and Fair Value of Related Debt Securities Held to Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Fair Value
Less than Twelve Months	$ 1,440,435	$ 37,894
More than Twelve Months	242,949	31,100
Total	1,683,384	68,994
Unrealized Losses
Less than Twelve Months	(22,830)	(351)
More than Twelve Months	(11,242)	(7,374)
Total	(34,072)	(7,725)
Obligations of states and state agencies
Fair Value
Less than Twelve Months	17,000	5,546
More than Twelve Months	5,517	0
Total	22,517	5,546
Unrealized Losses
Less than Twelve Months	(254)	(105)
More than Twelve Months	(58)	0
Total	(312)	(105)
Municipal bonds
Fair Value
Less than Twelve Months	9,403
More than Twelve Months	0
Total	9,403
Unrealized Losses
Less than Twelve Months	(87)
More than Twelve Months	0
Total	(87)	0
Total obligations of states and political subdivisions
Fair Value
Less than Twelve Months	26,403
More than Twelve Months	5,517
Total	31,920
Unrealized Losses
Less than Twelve Months	(341)
More than Twelve Months	(58)
Total	(399)	(105)
Residential mortgage-backed securities
Fair Value
Less than Twelve Months	1,381,405	21,599
More than Twelve Months	206,520	2,470
Total	1,587,925	24,069
Unrealized Losses
Less than Twelve Months	(22,365)	(245)
More than Twelve Months	(6,075)	(9)
Total	(28,440)	(254)
Trust preferred securities
Fair Value
Less than Twelve Months	0	0
More than Twelve Months	30,912	28,630
Total	30,912	28,630
Unrealized Losses
Less than Twelve Months	0	0
More than Twelve Months	(5,109)	(7,365)
Total	(5,109)	(7,365)
Corporate and other debt securities
Fair Value
Less than Twelve Months	32,627	10,749
More than Twelve Months	0	0
Total	32,627	10,749
Unrealized Losses
Less than Twelve Months	(124)	(1)
More than Twelve Months	0	0
Total	$ (124)	$ (1)