Derivatives and Hedging Activities (Interest Rate Contract Derivative Financial Instruments and Related Hedged Items) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Notional amount of interest rate derivatives	$ 6,280,814	$ 6,423,718
Interest rate derivative assets, fair value	138,332	43,686
Interest rate derivative liabilities, fair value	$ (49,482)	$ (19,029)
Derivatives designated as cash flow hedges | Pay-fixed interest rate swaps
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)	2.41%	2.37%
Weighted average remaining maturity of interest rate derivatives (in Duration)	2 years 7 months 6 days	3 years 2 months 12 days
Notional amount of interest rate derivatives	$ 2,921,000	$ 3,131,000
Derivatives designated as cash flow hedges | Pay-fixed interest rate swaps | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative liabilities, fair value	(6,566)	(1,607)
Derivatives designated as cash flow hedges | Pay-fixed interest rate swaps | Other Assets
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value	$ 0	$ 0
Derivatives designated as cash flow hedges | Interest Rate Contract [Member]
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)	1.55%
Weighted average remaining maturity of interest rate derivatives (in Duration)	9 months 18 days
Notional amount of interest rate derivatives	$ 250,000
Derivatives designated as cash flow hedges | Interest Rate Contract [Member] | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative liabilities, fair value	0
Derivatives designated as cash flow hedges | Interest Rate Contract [Member] | Other Assets
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value	$ 0
Derivatives not designated as hedges | Pay-fixed interest rate swaps
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)	3.68%	3.72%
Weighted average remaining maturity of interest rate derivatives (in Duration)	5 years 10 months 24 days	6 years 4 months 24 days
Notional amount of interest rate derivatives	$ 1,528,952	$ 1,460,355
Derivatives not designated as hedges | Pay-fixed interest rate swaps | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative liabilities, fair value	(42,916)	(15,307)
Derivatives not designated as hedges | Pay-fixed interest rate swaps | Other Assets
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value	$ 0	$ 876
Derivatives not designated as hedges | Interest Rate Contract [Member]
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)		1.55%
Weighted average remaining maturity of interest rate derivatives (in Duration)		1 year 7 months 6 days
Notional amount of interest rate derivatives		$ 250,000
Derivatives not designated as hedges | Interest Rate Contract [Member] | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative liabilities, fair value		0
Derivatives not designated as hedges | Interest Rate Contract [Member] | Other Assets
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value		$ 0
Derivatives not designated as hedges | Pay-variable interest rate swaps
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)	3.68%	3.72%
Weighted average remaining maturity of interest rate derivatives (in Duration)	5 years 10 months 24 days	6 years 4 months 24 days
Notional amount of interest rate derivatives	$ 1,528,952	$ 1,460,355
Derivatives not designated as hedges | Pay-variable interest rate swaps | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative liabilities, fair value	0	(2,115)
Derivatives not designated as hedges | Pay-variable interest rate swaps | Other Assets
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value	$ 138,332	$ 42,810
Derivatives not designated as hedges | Interest rate caps purchased, indexed to 1-month Libor [Domain]
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)	3.71%	3.30%
Weighted average remaining maturity of interest rate derivatives (in Duration)	8 months 12 days	7 months 6 days
Notional amount of interest rate derivatives	$ 25,955	$ 61,004
Derivatives not designated as hedges | Interest rate caps purchased, indexed to 1-month Libor [Domain] | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value	0
Derivatives not designated as hedges | Interest rate caps purchased, indexed to 1-month Libor [Domain] | Other Assets
Derivatives Fair Value [Line Items]
Interest rate derivative assets, fair value	$ 0	$ 0
Derivatives not designated as hedges | Interest rate caps sold, indexed to 1-month Libor [Domain] [Domain]
Derivatives Fair Value [Line Items]
Weighted average fixed rate of interest rate derivatives (in Percent)	3.71%	3.30%
Weighted average remaining maturity of interest rate derivatives (in Duration)	8 months 12 days	7 months 6 days
Notional amount of interest rate derivatives	$ 25,955	$ 61,004
Derivatives not designated as hedges | Interest rate caps sold, indexed to 1-month Libor [Domain] [Domain] | Other Liabilities
Derivatives Fair Value [Line Items]
Interest rate derivative liabilities, fair value	$ 0	$ 0