Loss Reserves (Details) (USD $)	3 Months Ended					6 Months Ended				12 Months Ended				36 Months Ended
	Jun. 30, 2013 Loan		Sep. 30, 2012 Notice Loan	Jun. 30, 2012 Loan		Jun. 30, 2013 Loan		Jun. 30, 2012 Loan		Dec. 31, 2012 Loan		Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Loan
Loss Reserve [Roll Forward]
Net reserve at beginning of period			$ 4,108,590,000			$ 4,056,843,000		$ 4,557,512,000		$ 4,557,512,000
Less reinsurance recoverable			126,832,000			104,848,000		154,607,000		154,607,000
Net reserve at end of period	3,515,410,000	[1]		3,981,758,000	[1]	3,515,410,000	[1]	3,981,758,000	[1]	3,951,995,000	[2]			4,402,905,000	[2]
Losses and LAE incurred in respect of default notices related to:
Current year						468,332,000		674,076,000
Prior years						(5,850,000)	[3]	214,420,000	[3]
Subtotal						462,482,000	[4]	888,496,000	[4]
Losses and LAE paid in respect of default notices related to:
Current year						5,137,000		12,502,000
Prior years						897,178,000		1,297,566,000
Reinsurance terminations						(3,248,000)	[5]	(425,000)	[5]
Subtotal						899,067,000	[6]	1,309,643,000	[6]
Net reserve at end of period	3,515,410,000	[1]		3,981,758,000	[1]	3,515,410,000	[1]	3,981,758,000	[1]	3,951,995,000	[2]			4,402,905,000	[2]
Plus reinsurance recoverables	83,898,000			126,832,000		83,898,000		126,832,000		104,848,000				154,607,000
Reserve at end of period	3,599,308,000			4,108,590,000		3,599,308,000		4,108,590,000		4,056,843,000				4,557,512,000
Loss reserve reduction from rescission	100,000,000			600,000,000		100,000,000		600,000,000		200,000,000				700,000,000
Paid losses mitigated by rescission amount						100,000,000		100,000,000
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Change in loss reserves						(6,000,000)	[7]	214,000,000	[7]
Historical average period for uncured default to develop into paid claim						12 months
Premium refund liability, expected claim payments	137,000,000					137,000,000				134,000,000
Primary Default Inventory [Roll Forward]
Default inventory at beginning of period	126,610		153,990	160,473		139,845		175,639		175,639
New Notices	25,425			32,241		53,289		67,022
Cures	(25,450)			(26,368)		(56,572)		(63,512)
Paids (including those charged to a deductible or captive)	(9,051)			(11,738)		(18,496)		(23,647)
Rescissions and denials	(429)			(618)		(961)		(1,512)
Default inventory at end of period	117,105			153,990		117,105		153,990		139,845				175,639
Number of rescindable loans affected by Company's decision to suspend rescissions for Countrywide	2,650					2,650
Total potential claim payments of rescindable loans affected by Company's decision to suspend rescissions for Countrywide	195,000,000					195,000,000
Number of rescindable loans affected by Company's decision to suspend rescissions for a specific customer	310					310
Total potential claim payments of rescindable loans affected by Company's decision to suspend rescissions for a specific customer	21,000,000					21,000,000
Number of rescindable loans affected by Company's decision to suspend rescissions for all other customers	300					300
Total potential claim payments of rescindable loans affected by Company's decision to suspend rescissions for all other customers	21,000,000					21,000,000
Pool insurance notice inventory [Abstract]
Pool insurance notice inventory (in number of loans)	7,006			25,178		7,006		25,178		8,594
Number of notices removed from pool notice inventory			15,600
Aging of the Primary Default Inventory [Abstract]
3 months or less	18,760			24,488		18,760		24,488		23,282
3 months or less (in hundredths)	16.00%			16.00%		16.00%		16.00%		17.00%
4 - 11 months	26,377			38,400		26,377		38,400		34,688
4 - 11 months (in hundredths)	23.00%			25.00%		23.00%		25.00%		25.00%
12 months or more	71,968			91,102		71,968		91,102		81,875
12 months or more (in hundredths)	61.00%			59.00%		61.00%		59.00%		58.00%
Total primary default inventory	117,105			153,990		117,105		153,990		139,845				175,639
Total primary default inventory (in hundredths)	100.00%			100.00%		100.00%		100.00%		100.00%
Primary claims received inventory included in ending default inventory	10,637	[8]		13,421	[8]	10,637	[8]	13,421	[8]	11,731	[8]
Primary claims received inventory included in ending default inventory (in hundredths)	9.00%	[8]		9.00%	[8]	9.00%	[8]	9.00%	[8]	8.00%	[8]
Number of payments delinquent [Abstract]
3 payments or less	27,498			33,677		27,498		33,677		34,245
3 payments or less (in hundredths)	24.00%			22.00%		24.00%		22.00%		24.00%
4 - 11 payments	27,299			39,744		27,299		39,744		34,458
4 - 11 payments (in hundredths)	23.00%			26.00%		23.00%		26.00%		25.00%
12 payments or more	62,308			80,569		62,308		80,569		71,142
12 payments or more (in hundredths)	53.00%			52.00%		53.00%		52.00%		51.00%
Total primary default inventory	117,105			153,990		117,105		153,990		139,845				175,639
Total primary default inventory (in hundredths)	100.00%			100.00%		100.00%		100.00%		100.00%
Claims resolved by rescissions [Abstract]
Mitigation of paid losses by rescission of policies						70,000,000				300,000,000				3,000,000,000
Percentage of claims received in a quarter resolved by rescission, lower range limit (in hundredths)						7.00%
Percentage of claims received in a quarter resolved by rescission, upper range limit (in hundredths)						28.00%
Estimated Rescission Reduction - Loss Reserve [Roll Forward]
Estimated rescission reduction - losses incurred										(200,000,000)		200,000,000	2,500,000,000
Estimated rescission reduction - ending reserve	100,000,000					100,000,000				200,000,000
Rescissions dispute period not ended (in hundredths)	37.00%					37.00%
Premium refund liability, expected future rescissions	14,000,000					14,000,000				18,000,000
Statute of limitations to bring legal proceedings disputing right to rescind coverage						3 years
Increase (Decrease) in Estimated Claim Rate On primary Defaults [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Change in loss reserves						0	[7]	230,000,000	[7]
Percentage of prior year default inventory resolved (in hundredths)						37.00%		35.00%
Increase (Decrease) in Estimated Severity, Primary Defaults [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Change in loss reserves						1,000,000	[7]	0	[7]
Change In Estimates Related to Pool Reserves, LAE Reserves and Reinsurance [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Change in loss reserves						$ (7,000,000)	[7]	$ (16,000,000)	[7]

[1] At June 30, 2013 and 2012, the estimated reduction in loss reserves related to rescissions approximated $0.1 billion and $0.6 billion, respectively.

[2] At December 31, 2012 and 2011, the estimated reduction in loss reserves related to rescissions approximated $0.2 billion and $0.7 billion, respectively.

[3] A negative number for prior year losses incurred indicates a redundancy of prior year loss reserves, and a positive number for prior year losses incurred indicates a deficiency of prior year loss reserves.

[4] Rescissions did not have a significant impact on incurred losses in the six months ended June 30, 2013 or 2012.

[5] In a termination, the reinsurance agreement is cancelled, with no future premium ceded and funds for any incurred but unpaid losses transferred to us. The transferred funds result in an increase in our investment portfolio (including cash and cash equivalents) and a decrease in net losses paid (reduction to losses incurred). In addition, there is an offsetting decrease in the reinsurance recoverable (increase in losses incurred), and thus there is no net impact to losses incurred.

[6] Rescissions mitigated our paid losses by an estimated $0.1 billion in each of the six months ended June 30, 2013 and 2012, which excludes amounts that may have been applied to a deductible.

[7] A negative number for prior year loss development indicates a redundancy of prior year loss reserves, and a positive number indicates a deficiency of prior year loss reserves.

[8] Our claims received inventory includes suspended rescission as discussed in Note 5 – “Litigation and Contingencies.” In connection with the Countrywide proceedings, we have voluntarily suspended rescissions of coverage related to loans that we believed would be included in a potential resolution. As of June 30, 2013, coverage on approximately 2,650 loans, representing total potential claim payments of approximately $195 million, that we had determined was rescindable was affected by our decision to suspend such rescissions. Substantially all of these potential rescissions relate to claims received beginning in the first quarter of 2011 or later. As of June 30, 2013, coverage on approximately 310 loans, representing total potential claim payments of approximately $21 million, was affected by our decision to suspend rescissions for another customer for which we also consider settlement probable. In addition, as of June 30, 2013, coverage on approximately 300 loans, representing total potential claim payments of approximately $21 million, was affected by our decision to suspend rescissions for customers other than those for which we consider settlement probable, as defined in ASC 450-20.