Summary of Significant Accounting Policies Impairment of Long-Lived Assets (Including Goodwill) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Impairment of assets	$ 0	$ 0.4	$ 6.3
Goodwill	0	39.4
Other Material Impairments	0	0	0
Atoka [Member]
Impairment of assets			5.0
Impairment of Assets Noncontrolling Interest Portion			$ 2.5