Borrowings Under Credit Facilities and Commercial Paper Program - Unsecured Revolving Credit Facility (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Disclosure [Abstract]
Balance outstanding at quarter end	$ 0	$ 655,000	$ 0	$ 655,000
Maximum amount outstanding at any month end	0	1,565,000	205,000	1,565,000
Average amount outstanding (total of daily principal balances divided by days in period)	$ 0	$ 1,047,631	$ 21,703	$ 937,045
Weighted average interest rate (actual interest expense divided by average borrowings outstanding)	0.00%	2.76%	5.05%	1.58%