Separation Costs and Activities (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Separation expense	$ 8.3	$ 0.0	$ 9.8	$ 0.0
Officers and Employees [Member] | Restricted Stock [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options Expiration Period of Restrictions			third anniversary
April 8, 2015 [Member] | Restricted Stock [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			0.4
April 8, 2015 [Member] | Officers and Employees [Member] | Restricted Stock [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options Expiration Period of Restrictions			second