Capital Stock (Details) - USD ($)	1 Months Ended	12 Months Ended
	Feb. 25, 2019	Dec. 31, 2018	Jan. 17, 2019	Dec. 31, 2017	May 08, 2017
Subsequent Event [Line Items]
Shares of common stock authorized (in shares)		100,000,000		100,000,000
Shares issued and outstanding (in shares)		49,700,000		50,500,000
Maximum shares allowed for issuance (in shares)		2,000,000.0
Par value (in dollars per share)		$ 10
Stock repurchase program amount					$ 200,000,000
Stock repurchase program remaining amount		$ 106,000,000
Stock repurchased and retired during period, shares		610,177
Stock repuchase program amount used		$ 43,500,000
Average price per share (in dollars per share)		$ 71.22
Subsequent Event
Subsequent Event [Line Items]
Dividend declared (in dollars per share)			$ 0.15
ASR December 2018
Subsequent Event [Line Items]
Accelerated share repurchases payment		$ 50,000,000
Stock repurchased and retired during period, shares		700,000
ASR initial price per share (in dollars per share)		$ 71.43
ASR February 2019 | Subsequent Event
Subsequent Event [Line Items]
Stock repurchased and retired during period, shares	37,387
ASR, final price per share (in dollars per share)	$ 67.81