Senior Notes (Summary of Senior Notes) (Parenthetical) (Details) - USD ($) $ in Thousands			1 Months Ended	9 Months Ended
	Feb. 15, 2030	Oct. 27, 2017	Jul. 31, 2016	Sep. 30, 2023	Dec. 31, 2022	May 31, 2020	Oct. 31, 2017	Jul. 31, 2014
Debt Instrument [Line Items]
Long-term Debt				$ 1,115,360	$ 1,114,554
Senior notes 4.25% due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage				4.25%	4.25%
Long-term Debt								$ 300,000
Debt instrument, maturity date				Jul. 31, 2024
Redemption price, percentage of principal amount				100.00%
Additional issuance of long-term debt			$ 200,000
Senior notes 4.00% due 2030 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage				4.00%	4.00%
Long-term Debt						$ 400,000
Debt instrument, maturity date				May 31, 2030
Senior notes 4.00% due 2030 [Member] | After February 15, 2030 [Member]
Debt Instrument [Line Items]
Redemption price, percentage of principal amount				100.00%
Senior notes 4.00% due 2030 [Member] | Measurement Input, Discount Rate [Member] | Prior to February 15, 2030 [Member]
Debt Instrument [Line Items]
Redemption at treasury rate basis point				0.50%
Senior notes 4.00% due 2030 [Member] | Forecast [Member]
Debt Instrument [Line Items]
Redemption price, percentage of principal amount	100.00%
Senior notes 5.20% due 2047 [Member]
Debt Instrument [Line Items]
Debt Instrument Interest Rate Stated Percentage				5.20%	5.20%
Long-term Debt							$ 200,000
Debt instrument, maturity date				Oct. 31, 2047
Redemption price, percentage of principal amount				100.00%
Additional issuance of long-term debt		$ 25,000