Summary of Significant Accounting Policies (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2020	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash on hand or on deposit required		$ 42,000
Cash collateral on deposit	$ 110,300	74,000
Foreclosed assets	3,400	850
Real Estate Owned, Valuation Allowance, Provision	$ 14	$ 231	$ 0
Amount of significant concentrations of any properties with write downs from any single geographic region	0.00%	0.00%	0.00%
Cumulative effect of accounting change			$ (29,252)			$ (14,672)
Operating Lease, Right-of-Use Asset	$ 281,438	$ 292,087
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Range of change in fair value of derivative hedging instrument to be considered highly effective	80.00%
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Range of change in fair value of derivative hedging instrument to be considered highly effective	125.00%
Premises and Equipment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 281,400	292,100			$ 170,500
Other Liabilities [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, liability	$ 313,404	$ 323,000			174,400
Retained Earnings [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of accounting change			$ (29,252)	$ (29,300)	$ (14,700)	$ (14,672)