Municipal Bond Guarantee (Details) (USD $) In Millions, unless otherwise specified		3 Months Ended	6 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended			1 Months Ended	6 Months Ended			6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014 BAM Contract	Jun. 30, 2014 BAM Contract	Dec. 31, 2013 BAM Contract	Jul. 31, 2012 HG Global	Jun. 30, 2014 HG Global	Jun. 30, 2013 HG Global	Jun. 30, 2014 HG Global	Jun. 30, 2013 HG Global	Jun. 30, 2014 HG Global Preferred Stock	Jun. 30, 2014 HG Global Common Stock	Jun. 30, 2014 Build America Mutual	Jun. 30, 2013 Build America Mutual	Jun. 30, 2014 Build America Mutual	Jun. 30, 2013 Build America Mutual	Jun. 30, 2014 HG Re	Jul. 31, 2012 BAM Management	Jun. 30, 2014 Surplus Note BAM	Jun. 30, 2014 Fixed interest rate Surplus Note BAM	Jun. 30, 2014 Variable Rate Surplus Note BAM	Jun. 30, 2014 Combination One Surplus Note BAM Y	Jun. 30, 2014 Combination Two Surplus Note BAM Y
Guarantor Obligations [Line Items]
basis points																		300.00%
Municipal bond contract		1,144	1,144	701
Insured Financial Obligations, Remaining Weighted Average Contract Period			13 years 1 month 5 days	13 years 9 months 21 days
Municipal bond outstanding principal		$ 7,767.7	$ 7,767.7	$ 4,703.7
Municipal bond outstanding interest		4,897.2	4,897.2	3,264.4
Municipal bond debt service outstanding		12,664.9	12,664.9	7,968.1
Partners Capital Contribution					594.5												14.5
Ownership interest (as a percent)										96.90%	88.40%
Surplus Notes					503.0
Statutory Accounting Practices, Statutory Capital and Surplus, Balance																443.5
Percentage of par value of policy reinsured	15.00%					15.00%		15.00%
Income (Loss) from Continuing Operations before Income Taxes, Domestic		4.0	7.9			5.0	7.8	9.6	17.7			(8.0)	(26.7)	(16.6)	(45.1)
Interest income (expense), surplus notes								10.0	20.1			(4.0)	(10.0)	(7.9)	(20.1)
Number of years of change in interest rate																					5	3
Financial Guarantee Insurance Contracts, Unearned Premium Revenue		$ 19.7	$ 19.7	$ 13.2
Debt Instrument, Interest Rate, Stated Percentage																			8.00%	3.13%
Year of U.S. Treasury Rate				1