Derivative Instruments and Hedging Activities Interest Spread on Interest Rate Swaps and Caps (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 8,076,933,000	$ 55,549,424,000	$ 8,076,933,000	$ 55,549,424,000	$ 60,549,307,000	$ 48,445,497,000	$ 58,777,783,000	$ 36,528,169,000
Average Notional Amount	48,601,803,000	57,194,079,000	49,922,003,000	52,476,177,000
Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net interest expense (income) on interest rate swaps and caps	(56,300,000)	22,900,000	(68,900,000)	46,600,000
Net Long Position [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Average Notional Amount	$ 45,800,000,000	$ 40,700,000,000	$ 44,300,000,000	$ 39,100,000,000