Derivatives - Derivatives Associated With Cash Flow Hedges (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Mar. 31, 2017	Mar. 31, 2016
Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Notional	$ 800,000	$ 800,000
Cash Flow Hedge | Hedging Instruments And Hedged Items
Derivative Instruments, Gain (Loss) [Line Items]
Notional				$ 650,000
Variability in cash flows related to debt instruments (primarily loans)					$ 250,000
Cash Flow Hedge | Hedging Instruments And Hedged Items | Interest Rate Contract
Derivative Instruments, Gain (Loss) [Line Items]
Variability in cash flows related to debt instruments (primarily loans)	1,500,000	1,500,000	$ 900,000
Cash Flow Hedge | Hedging Instruments And Hedged Items | Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Notional	1,500,000	1,500,000	900,000
Assets	35,606	35,606
Liabilities			$ 241
Mortgage Banking Hedges | Hedging Instruments And Hedged Items | Interest Rate Lock
Derivative Instruments, Gain (Loss) [Line Items]
Notional	698,744	698,744
Assets	21,677	21,677
Liabilities	223	223
Gain (loss) on derivative instruments	7,434	7,434
Mortgage Banking Hedges | Hedging Instruments And Hedged Items | Forward Sales Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional	753,660	753,660
Assets	859	859
Liabilities	2,577	2,577
Gain (loss) on derivative instruments	$ (9,633)	$ (9,633)