Securities Available for Sale and Held to Maturity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2013
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Reclassification of Securities available for sale to securities held to maturity				$ 1,099,000,000.000
Net unrealized holding loss on AFS Securities at date of transfer				46,600,000
Net unrealized holding losses on AFS Securities, net of tax at date of transfer				$ 28,800,000
Net unamortized, unrealized loss on transfer of securities	$ 6,300,000	$ 8,900,000
Net unamortized, unrealized loss on transfer of securities, net of tax	4,700,000	6,700,000
Credit loss recognized	0	0
Potential credit loss exposure	7,300,000	26,600,000
Securities held to maturity	342,537,000	538,072,000
Other-than-temporary impairments			$ 0
Pledged to collateralize public deposits and securities sold under repurchase agreements and for other purposes as permitted by law	2,831,000,000	1,964,000,000
Pledged securities providing additional contingency funding	0	0
Realized gains or losses on security	0	0	$ 0
30 Days or More Past Due [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Securities held to maturity	0	0
Securities Available for Sale [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	5,100,000	4,000,000.0
Securities Held to Maturity [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Accrued interest receivable	670,000	1,200,000
Reserve for credit loss	0	0
Held-to-maturity nonnaccrual	$ 0	$ 0