Subsequent Events (Details) - Senior Notes [Member] - USD ($)			1 Months Ended
	Feb. 17, 2021	Feb. 09, 2021	Oct. 31, 2019	Dec. 31, 2020	Sep. 30, 2019	Apr. 15, 2015
$400 Million 5% Senior Notes [Member]
Subsequent Event [Line Items]
Face amount				$ 400,000,000		$ 400,000,000.0
Stated interest rate (as a percent)				5.00%		5.00%
$700 Million 4.75% Senior Note [Member]
Subsequent Event [Line Items]
Face amount			$ 700,000,000	$ 700,000,000	$ 700,000,000
Stated interest rate (as a percent)			4.75%	4.75%	4.75%
Redemption price (as a percent)			100.00%
Subsequent event | $400 Million 5% Senior Notes [Member]
Subsequent Event [Line Items]
Face amount	$ 400,000,000	$ 400,000,000
Stated interest rate (as a percent)	5.00%	5.00%
Redemption price of per thousand		$ 1,005.00
Subsequent event | $600 Million 4.50% Senior Notes [Member]
Subsequent Event [Line Items]
Face amount	$ 600,000,000
Stated interest rate (as a percent)	4.50%
Proceeds from Issuance of Debt	$ 591,000,000
Subsequent event | $700 Million 4.75% Senior Note [Member]
Subsequent Event [Line Items]
Face amount	$ 700,000,000
Stated interest rate (as a percent)	4.75%