Borrowings Under Credit Facilities and Commercial Paper Program - Aggregate Borrowings Under Unsecured Revolving Credit Facility and Commercial Paper (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Disclosure [Abstract]
Balance outstanding at quarter end	$ 300,000	$ 0
Maximum amount outstanding at any month end	995,660	0
Average amount outstanding (total of daily principal balances divided by days in period)	$ 961,463	$ 0
Weighted average interest rate (actual interest expense divided by average borrowings outstanding)	0.53%	0.00%