Commitments and Contingencies - Consolidated Statements of Financial Condition Related to Fair Value of Derivative Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Interest rate caps and swaps
Derivative [Line Items]
Other Assets	$ 0	$ 0
Other Liabilities	150,487	17,218
Derivatives designated as hedging instruments:
Derivative [Line Items]
Notional Amount	1,100,000	187,281
Derivatives not designated as hedging instruments:
Derivative [Line Items]
Notional Amount	9,211,043	4,255,866
Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Notional Amount	8,889,557	4,113,106
Derivatives not designated as hedging instruments: | Mortgage banking derivatives
Derivative [Line Items]
Notional Amount	321,486	142,760
Other Assets | Derivatives designated as hedging instruments:
Derivative [Line Items]
Other Assets	0	0
Other Assets | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Other Assets	387,452	158,532
Other Assets | Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Other Assets	387,008	158,382
Other Assets | Derivatives not designated as hedging instruments: | Mortgage banking derivatives
Derivative [Line Items]
Other Assets	444	150
Other Liabilities | Derivatives designated as hedging instruments:
Derivative [Line Items]
Other Liabilities	179	1,713
Other Liabilities | Derivatives not designated as hedging instruments:
Derivative [Line Items]
Other Liabilities	156,102	42,213
Other Liabilities | Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Other Liabilities	154,025	42,020
Other Liabilities | Derivatives not designated as hedging instruments: | Mortgage banking derivatives
Derivative [Line Items]
Other Liabilities	2,077	193
Cash flow hedge | Derivatives designated as hedging instruments: | Interest rate caps and swaps
Derivative [Line Items]
Notional Amount	1,100,000	180,000
Cash flow hedge | Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Notional Amount	1,100,000
Cash flow hedge | Other Assets | Derivatives designated as hedging instruments: | Interest rate caps and swaps
Derivative [Line Items]
Other Assets	0	0
Cash flow hedge | Other Liabilities | Derivatives designated as hedging instruments: | Interest rate caps and swaps
Derivative [Line Items]
Other Liabilities	179	1,484
Fair value hedge | Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Notional Amount	0	7,281
Fair value hedge | Derivatives not designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Notional Amount	10,400
Fair value hedge | Other Assets | Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Other Assets	0	0
Fair value hedge | Other Liabilities | Derivatives designated as hedging instruments: | Interest rate swaps
Derivative [Line Items]
Other Liabilities	$ 0	$ 229