Derivative Instruments and Hedging Activities Interest Spread on Interest Rate Swaps and Caps (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 49,205,497,000	$ 36,528,169,000	$ 31,226,878,000
Average Notional Amount	52,764,012,000	31,823,176,000
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net interest expense (income) on interest rate swaps and caps	70,500,000	49,200,000	(8,800,000)
Net Long Position [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Average Notional Amount	$ 40,000,000,000.0	$ 29,400,000,000	$ 19,400,000,000