Capital Stock (Details) - USD ($)	Jan. 15, 2018	Dec. 31, 2017	May 08, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Shares of common stock authorized (in shares)		100,000,000		100,000,000
Shares issued and outstanding (in shares)		50,500,000		50,000,000
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		$ 200,000,000
Subsequent Event
Subsequent Event [Line Items]
Dividend declared (in dollars per share)	$ 0.15