Asset Impairment Asset Impairment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Asset impairment	$ (31.1)	$ (0.1)	$ (31.2)	$ (0.4)
Assets Held-for-sale, Long Lived, Fair Value Disclosure	175.0		175.0		$ 7.0
Portfolio Proceeds			298.2	181.8
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			69.7	55.1
Nordic Vessels [Member]
Segment Reporting Information [Line Items]
Asset impairment	30.8
Portfolio Management [Member]
Segment Reporting Information [Line Items]
Asset impairment	(31.0)	$ 0.0	(31.0)	$ 0.1
Assets Held-for-sale, Long Lived, Fair Value Disclosure	39.7		$ 39.7
Portfolio Proceeds	31.6
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	$ (7.3)
Cardinal Marine [Domain]
Segment Reporting Information [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	100.00%		100.00%
Asset impairment	$ 19.0
Assets Held-for-sale, Long Lived, Fair Value Disclosure	25.2		$ 25.2
Cardinal Marine [Domain] | Portfolio Management [Member]
Segment Reporting Information [Line Items]
Asset impairment	$ 49.8