Shareholders' Equity - Share Issuance (Details) (USD $)	0 Months Ended		12 Months Ended
	Jun. 01, 2012		Dec. 31, 2014 vote	Dec. 31, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Authorized share capital			$ 5,000,000
Common stock, shares authorized			500,000,000	500,000,000
Common stock par value (per share)			$ 0.01	$ 0.01
Number of votes per share of common stock			1
Percentage of controlled shares			9.50%
Price per share of stock issued (in dollars per share)	$ 12.85	[1]
Proceeds from issuances of common stock	173,000,000	[1]	0	0	173,000,000
Proceeds from issuance of common stock, net proceeds	$ 173,000,000	[1]
Percentage of voting power held by one shareholder			75.00%
Assured Guaranty LTD [Member]
Class of Stock [Line Items]
Common stock issuance, net (in shares)	13,428,770	[1]

[1] Relates to the settlement of forward purchase contracts. See Note 17, Long-Term Debt and Credit Facilities.