Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Dec. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 29, 2021	Dec. 31, 2020
Reclassification [Line Items]
Net change in deposits		$ 1,259,172	$ 2,151,400
Net change in cash and cash equivalents		515,558	1,384,870
Assets		41,274,228			$ 40,686,076
Loans		32,118,130			31,876,869
Deposits		$ 33,194,774			$ 31,935,602
Westchester Bank Holding Corporation | Scenario, forecast
Reclassification [Line Items]
Number of shares issued for every share owned (in shares)	229.645
Business combination, consideration transferred, equity interests issued and issuable	$ 210,000
Payments to acquire business	$ 10,000
Westchester Bank Holding Corporation
Reclassification [Line Items]
Assets				$ 1,300,000
Loans				908,000
Deposits				$ 1,100,000
Previously Reported
Reclassification [Line Items]
Net change in deposits			90,800
Net change in cash and cash equivalents			$ 1,500,000