Investment Securities Gross Unrealized Losses and Fair Values of Investments by Category and Length of Time in a Continuous Unrealized Loss Position (Details) $ in Thousands	Dec. 31, 2021 USD ($) Security	Dec. 31, 2020 USD ($) Security
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	89	22
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 917,933	$ 266,636
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (13,925)	$ (1,660)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	119	163
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 91,336	$ 105,077
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	(2,331)	(3,618)
Debt Securities, Available-for-sale, Unrealized Loss Position	1,009,269	371,713
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (16,256)	$ (5,278)
Held to Maturity
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	50
Estimated Fair Value, Less Than 12 Months	$ 762,923
Unrealized Losses, Less Than 12 Months	$ (25,539)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0
Estimated Fair Value, 12 Months or Longer	$ 0
Unrealized Losses, 12 Months or Longer	0
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	762,923
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	$ (25,539)
U.S. Government securities
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 127,618
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (213)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Unrealized Loss Position	127,618
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (213)
State and municipal securities
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	29
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 82,731
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (678)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0
Debt Securities, Available-for-sale, Unrealized Loss Position	82,731
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (678)
Corporate debt securities
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	6	9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 43,068	$ 44,528
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (358)	$ (377)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0	$ 6,871
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	(314)
Debt Securities, Available-for-sale, Unrealized Loss Position	43,068	51,399
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (358)	$ (691)
Collateralized mortgage obligations
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	4	3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 28,517	$ 57,601
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (754)	$ (115)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	28,517	57,601
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (754)	$ (115)
Residential mortgage-backed securities
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	7	1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 123,687	$ 20,124
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (2,388)	$ (27)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	1	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 16,669	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	(648)	0
Debt Securities, Available-for-sale, Unrealized Loss Position	140,356	20,124
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (3,036)	$ (27)
Held to Maturity
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	14
Estimated Fair Value, Less Than 12 Months	$ 205,969
Unrealized Losses, Less Than 12 Months	$ (7,067)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0
Estimated Fair Value, 12 Months or Longer	$ 0
Unrealized Losses, 12 Months or Longer	0
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	205,969
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	$ (7,067)
Commercial mortgage-backed securities
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	41	9
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 512,312	$ 144,383
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (9,534)	$ (1,141)
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	0	0
Debt Securities, Available-for-sale, Unrealized Loss Position	512,312	144,383
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (9,534)	$ (1,141)
Held to Maturity
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	36
Estimated Fair Value, Less Than 12 Months	$ 556,954
Unrealized Losses, Less Than 12 Months	$ (18,472)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	0
Estimated Fair Value, 12 Months or Longer	$ 0
Unrealized Losses, 12 Months or Longer	0
Debt Securities, Held-to-maturity, Unrealized Loss Position, Fair Value	556,954
Debt Securities, Held-to-maturity, Unrealized Loss Position, Accumulated Loss	$ (18,472)
Auction rate securities
Available for Sale
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Number of Positions \| Security	0	0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 0	$ 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Number of Positions \| Security	118	162
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	$ 74,667	$ 98,206
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer	(1,683)	(3,304)
Debt Securities, Available-for-sale, Unrealized Loss Position	74,667	98,206
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss	$ (1,683)	$ (3,304)

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