Municipal Bond Guarantee (Details) (USD $) In Millions, unless otherwise specified		1 Months Ended	3 Months Ended	9 Months Ended						3 Months Ended	9 Months Ended	12 Months Ended		1 Months Ended
	Sep. 30, 2013	Jul. 31, 2012 HG Global	Sep. 30, 2013 HG Global	Sep. 30, 2013 HG Global	Dec. 31, 2012 HG Global	Sep. 30, 2013 HG Global Preferred Stock	Dec. 31, 2012 HG Global Preferred Stock	Sep. 30, 2013 HG Global Common Stock	Dec. 31, 2012 HG Global Common Stock	Sep. 30, 2013 Build America Mutual	Sep. 30, 2013 Build America Mutual	Dec. 31, 2012 Build America Mutual	Sep. 30, 2013 HG Re [Member]	Jul. 31, 2012 BAM Management
Guarantor Obligations [Line Items]
Municipal bond contract										483	483	3
Insured Financial Obligations with Credit Deterioration, Remaining Weighted Average Contract Period											13 years 8 months 15 days	10 years 4 months 24 days
Municipal bond outstanding principal										$ 3,128.3	$ 3,128.3	$ 25.8
Municipal bond outstanding interest										1,824.6	1,824.6	8.9
Funds to Capitalized HG Global		594.5												14.5
Ownership interest (as a percent)						97.30%	97.30%	88.70%	88.70%
Surplus Notes		503.0			503.0
Statutory Accounting Practices, Statutory Capital and Surplus, Balance													428.2
Percentage of par value of policy reinsured	15.00%							15.00%
Income (Loss) from Continuing Operations before Income Taxes, Foreign			10.5	28.2						15.1	60.2
Interest income (expense), surplus notes			10.1	30.2						(10.1)	(30.2)
Financial Guarantee Insurance Contracts, Unearned Premium Revenue										$ 8.1	$ 8.1	$ 0.1