Commitments and Contingencies Commitments and Contingencies (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Additional Consulting Fees to Remediate Section 7702 and 72(s) Issues			$ 1.0	$ 0.0
Total costs to remediate IRC Section 7702 and 72(s) issues		$ 14.6	14.9
Toll charges and fees to remediate IRC Section 7702 and 72(s) issues			14.5
Cost of reserve liabilities to remediate IRC Section 7702 issue			0.4
Increase in total cost to remediate Section 7702 and 72(s) issues during the period	$ 0.3
Minimum [Member]
Loss Contingencies [Line Items]
Cost Range to Remediate IRC Section 7702 and 72(s) Issues			7.0
Minimum [Member] | IRC Section 7702 remediation costs [Member]
Loss Contingencies [Line Items]
Estimate of possible loss	1.0		1.0
Maximum [Member]
Loss Contingencies [Line Items]
Cost Range to Remediate IRC Section 7702 and 72(s) Issues			43.8
Maximum [Member] | IRC Section 7702 remediation costs [Member]
Loss Contingencies [Line Items]
Estimate of possible loss	$ 1.5		$ 1.5