Commitments and Contingencies Commitments and Contingencies (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Total costs to remediate IRC Section 7702 issue		$ 11,400,000
Toll charges and fees to remediate IRC Section 7702 issue		10,100,000
Cost of claim and reserve liabilities to remediate IRC Section 7702 issue		$ 1,300,000
Toll Charges and Fees to Remediate IRC Section 72(s)	$ 2,500,000.0
IRC Section 7702 remediation costs [Member]
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum	500,000
Loss Contingency, Range of Possible Loss, Maximum	800,000
Minimum [Member]
Loss Contingencies [Line Items]
Cost Range to Remediate IRC Section 7702 and 72(s) Issue	13,900,000
Maximum [Member]
Loss Contingencies [Line Items]
Cost Range to Remediate IRC Section 7702 and 72(s) Issue	$ 46,600,000