Capital Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 06, 2012	Mar. 05, 2012
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Shares of common stock authorized	100,000,000	100,000,000
Shares issued and outstanding	48,600,000	48,400,000
Shares of Common Stock for Pension Plan Contribution			361,446
Shares of Common Stock for Defined Benefit Plan Contribution - Value per Share				$ 24.9
Value of Shares of Common Stock for Defined Benefit Plan Contribution		$ 0	$ 9.0
Date of shares issued for stock contribution	Mar. 06, 2012
Discount due to lack of marketability					2.40%
Closing share price					$ 25.51
Regular Quarterly Dividend Date Declared	Jan. 22, 2015
Regular Quarterly Dividend Payable - Amount per Share	$ 0.1
Regular Quarterly Dividend Date Payable	Mar. 02, 2015
Amount of Shares of Preferred Stock Authorized to be Issued	2,000,000
Common Stock Shares Available under Shelf Registration	141,500,000
Par Value of Preferred Stock Authorized to be Issued	$ 10