Stock Repurchase Plans and Shareholder Rights Plan (Details)	3 Months Ended		9 Months Ended		43 Months Ended
	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($) $ / shares	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($) $ / shares	Oct. 23, 2020 USD ($) $ / shares shares	Aug. 31, 2020 USD ($)	Mar. 31, 2020 USD ($) item $ / shares	Dec. 31, 2019 $ / shares	Mar. 30, 2017 USD ($)
Stock Repurchase Plans and Shareholder Rights Plan
Value of shares repurchased	$ 48,000	$ 48,000	$ 54,000	$ 52,000
Amount of reduction in incremental revolving credit commitments required to allow repurchase of common stock						$ 131,000,000
Par value | $ / shares	$ 1.00	$ 1.00	$ 1.00	$ 1.00				$ 1.00
Preferred share purchase right
Stock Repurchase Plans and Shareholder Rights Plan
Dividend, Preferred share purchase right							1
Share price | $ / shares							$ 75.00
Exercisable exercise price of the Right | item							2
Series B Junior Preferred Stock | Preferred share purchase right
Stock Repurchase Plans and Shareholder Rights Plan
Percentage of purchase of a preferred shares represented by rights							0.001
Par value | $ / shares							$ 1.00
March 2017 Stock Repurchase Plan
Stock Repurchase Plans and Shareholder Rights Plan
Amount authorized of shares to be repurchased under Stock Repurchase Program									$ 500,000,000.0
Total number of shares purchased (in shares) | shares					4,607,000
Value of shares repurchased					$ 268,300,000
Shares acquired, average cost (in dollars per share) | $ / shares					$ 58.25
Permitted dollar value of repurchases remaining					$ 231,700,000