Debt - 364-Day Revolving Credit Facility (Details) - 364-Day Credit Agreement - Unsecured Debt - Revolving Credit Facility		12 Months Ended
	Sep. 11, 2019 USD ($)	Dec. 31, 2019 USD ($) subsidiary
Line of Credit Facility [Line Items]
Credit facility, term	364 days	364 days
Maximum borrowing capacity	$ 1,000,000,000.0
Number of subsidiaries designated as additional borrowers | subsidiary		0
Borrowings outstanding		$ 0
Remaining borrowing capacity		$ 1,000,000,000.0
London Interbank Offered Rate (LIBOR) | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.875%
London Interbank Offered Rate (LIBOR) | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.375%
Prime Rate, The New York Federal Reserve Bank Rate Or London Interbank Offered Rate (LIBOR) | Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.00%
Prime Rate, The New York Federal Reserve Bank Rate Or London Interbank Offered Rate (LIBOR) | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate		0.375%