Expected Loss to be Paid - Net Expected Loss to be Paid After Recoveries for Breaches of R&W (Details) - USD ($) $ in Millions			12 Months Ended
		Apr. 01, 2015	Dec. 31, 2015		Dec. 31, 2014
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			$ 1,169	[1]	$ 982
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		$ 190
Total economic loss development			319		(30)
Accretion of discount			32
Changes in discount rates			(23)
Changes in timing and assumptions			310
(Paid) Recovered Losses After Recoveries for R&W	[2]		(287)		217
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		$ 1,391		1,169
Period after the end of the reporting period within which the ceded paid losses are typically settled (in days)			45 days
Loss and LAE Reserve paid			$ 25		37
Expected LAE to be paid			12		16
Residential Mortgage-Backed Securities (RMBS) [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			584	[1]	493
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		4
Total economic loss development			(82)		(268)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(97)		359
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		409		584
Residential Mortgage-Backed Securities (RMBS) [Member] | First Lien [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			595	[1]	620
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		3
Total economic loss development			(124)		(226)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(126)		201
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		348		595
Residential Mortgage-Backed Securities (RMBS) [Member] | First Lien [Member] | Financing Receivable, Prime [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			4	[1]	21
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		0
Total economic loss development			(1)		(16)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(5)		(1)
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		(2)		4
Residential Mortgage-Backed Securities (RMBS) [Member] | First Lien [Member] | Alt-A [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			304	[1]	304
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		7
Total economic loss development			(126)		(144)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(58)		144
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		127		304
Residential Mortgage-Backed Securities (RMBS) [Member] | First Lien [Member] | Option ARM [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			(16)	[1]	(9)
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		0
Total economic loss development			(16)		(59)
(Paid) Recovered Losses After Recoveries for R&W	[2]		4		52
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		(28)		(16)
Residential Mortgage-Backed Securities (RMBS) [Member] | First Lien [Member] | Subprime [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			303	[1]	304
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		(4)
Total economic loss development			19		(7)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(67)		6
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		251		303
Residential Mortgage-Backed Securities (RMBS) [Member] | Second Lien [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			(11)	[1]	(127)
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		1
Total economic loss development			42		(42)
(Paid) Recovered Losses After Recoveries for R&W			(29)		(158)
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		61		(11)
XXX Life Insurance Transaction [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			161	[1]	75
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		0
Total economic loss development			11		92
(Paid) Recovered Losses After Recoveries for R&W	[2]		(73)		(6)
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		99		161
Trust preferred securities (TruPS) [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			23	[1]	51
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		0
Total economic loss development			(18)		(28)
(Paid) Recovered Losses After Recoveries for R&W	[2]		0		0
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		5		23
Student Loan [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			68	[1]	52
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		0
Total economic loss development			(9)		16
(Paid) Recovered Losses After Recoveries for R&W	[2]		(5)		0
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		54		68
Other structured finance [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			(15)	[1]	(10)
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		101
Total economic loss development			12		(13)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(83)		8
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		15		(15)
Public Finance [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			348	[1]	321
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		85
Total economic loss development			405		171
(Paid) Recovered Losses After Recoveries for R&W	[2]		(29)		(144)
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		809		348
Public Finance [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			303	[1]	264
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		81
Total economic loss development			416		183
(Paid) Recovered Losses After Recoveries for R&W	[2]		(29)		(144)
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		771		303
Public Finance [Member] | Non United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			45	[1]	57
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		4
Total economic loss development			(11)		(12)
(Paid) Recovered Losses After Recoveries for R&W	[2]		0		0
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		38		45
Structured Finance [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Beginning of Period, Net Expected Loss To Be Paid After Recoveries of R&W			821	[1]	661
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015		105
Total economic loss development			(86)		(201)
(Paid) Recovered Losses After Recoveries for R&W	[2]		(258)		361
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W	[1]		582		$ 821
Radian [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
Net expected loss to be paid on Radian Asset portfolio as of April 1, 2015			$ 190
Radian [Member] | Other structured finance [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W		101
Radian [Member] | Public Finance [Member] | United States [Member]
Present Value of Net Expected Loss and Loss Adjustment Expenses to be Paid [Roll Forward]
End of Period, Net Expected Loss To Be Paid After Recoveries of R&W		$ 81

[1] Includes expected LAE to be paid of $12 million as of December 31, 2015 and $16 million as of December 31, 2014.

[2] Net of ceded paid losses, whether or not such amounts have been settled with reinsurers. Ceded paid losses are typically settled 45 days after the end of the reporting period. Such amounts are recorded in reinsurance recoverable on paid losses included in other assets. The Company paid $25 million and $37 million in LAE for the years ended December 31, 2015 and 2014, respectively.