Loss Reserves (Details) (USD $)	3 Months Ended					6 Months Ended	12 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Mar. 31, 2009	Jun. 30, 2009	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Loss Reserve [Roll Forward]
Reserve at beginning of period	$ 4,557,512,000		$ 5,884,171,000				$ 5,884,171,000
Less reinsurance recoverable	154,607,000		275,290,000				275,290,000
Net reserve at beginning of year	4,402,905,000	[1]	5,608,881,000	[1]			5,608,881,000	[1]
Losses and LAE incurred in respect of default notices received in [Abstract]
Current year	280,565,000		347,399,000
Prior years	56,523,000	[2]	(36,968,000)	[2]
Subtotal	337,088,000	[3]	310,431,000	[3]
Losses and LAE paid in respect of default notices received in [Abstract]
Current year	280,000		26,000
Prior years	673,257,000		686,748,000
Reinsurance terminations	(425,000)	[4]	(917,000)	[4]
Subtotal	673,112,000	[5]	685,857,000	[5]
Net reserve at end of period	4,066,881,000	[6]	5,233,455,000	[6]			4,402,905,000	[1]	5,608,881,000	[1]
Plus reinsurance recoverables	142,289,000		238,039,000				154,607,000		275,290,000
Reserve at end of period	4,209,170,000		5,471,494,000				4,557,512,000		5,884,171,000
Losses paid [Abstract]
Historical average period for uncured default to develop into paid claim (in months)	12M
Premium refund liability, expected claim payments	120,000,000						114,000,000
Aging of the Primary Default Inventory [Abstract]
3 months or less	22,516		27,744				31,456
3 months or less (in hundredths)	14.00%		14.00%				18.00%
4 - 11 months	45,552		57,319				46,352
4 - 11 months (in hundredths)	28.00%		29.00%				26.00%
12 months or more	92,405		110,822				97,831
12 months or more (in hundredths)	58.00%		57.00%				56.00%
Total primary default inventory	160,473		195,885				175,639		214,724
Total primary default inventory (in hundredths)	100.00%		100.00%				100.00%
Primary claims received inventory included in ending default inventory	12,758		17,686				12,610
Primary claims received inventory included in ending default inventory (in hundredths)	8.00%		9.00%				7.00%
Number of payments delinquent [Abstract]
3 payments or less	33,579		40,680				42,804
3 payments or less (in hundredths)	21.00%		21.00%				24.00%
4 - 11 payments	45,539		61,060				47,864
4 - 11 payments (in hundredths)	28.00%		31.00%				27.00%
12 payments or more	81,355		94,145				84,971
12 payments or more (in hundredths)	51.00%		48.00%				49.00%
Total primary default inventory	160,473		195,885				175,639		214,724
Total primary default inventory (in hundredths)	100.00%		100.00%				100.00%
Claims resolved by rescissions [Abstract]
Percentage of claims received in a quarter resolved by rescission, lower range limit (in hundredths)	13.00%
Percentage of claims received in a quarter resolved by rescission, upper range limit (in hundredths)	19.00%				28.00%	28.00%
Number of rescindable loans affected by Company's decision to suspend rescissions	860
Total potential claim payments of rescindable loans affected by Company's decision to suspend rescissions	65,000,000
Number of rescindable loans affected by Company's decision to suspend rescissions for customers other than Countrywide	250
Total potential claim payments of rescindable loans affected by Company's decision to suspend rescissions for customers other than Countrywide	16,000,000
Premium refund liability, expected future rescissions	49,000,000						58,000,000
Number of GSEs that have approved settlement agreements	1
Number of settlement agreements approved by one GSE	1
Estimated Rescission Reduction - Loss Reserve [Roll Forward]
Estimated rescission reduction - beginning reserve	700,000,000		1,300,000,000				1,300,000,000
Estimated rescission reduction - losses incurred	0		0
Rescission reduction - paid claims	100,000,000		200,000,000				600,000,000		1,200,000,000		1,200,000,000
Amounts that may have been applied to a deductible	0		0
Net rescission reduction - paid claims	100,000,000		200,000,000
Estimated rescission reduction - ending reserve	600,000,000		1,100,000,000				700,000,000		1,300,000,000
Statute of limitations to bring legal proceedings disputing right to rescind coverage (in years)	3Y
Primary Default Inventory [Roll Forward]
Default inventory at beginning of period	175,639		214,724				214,724
Plus: New Notices	34,781		43,195
Less: Cures	(37,144)		(45,639)
Less: Paids (including those charged to a deductible or captive)	(11,909)		(13,466)
Less: Rescissions and denials	894		(2,929)
Default inventory at end of period	160,473		195,885				175,639		214,724
Pool insurance notice inventory [Abstract]
Pool insurance notice inventory (in number of loans)	26,601		40,769				32,971
Increase (Decrease) in Severity, Primary Defaults [Member]
Losses incurred [Abstract]
Change in loss reserves			28,000,000
Percentage of prior year default inventory resolved (in hundredths)			22.00%
Increase (Decrease) in Expected Claim Rate [Member]
Losses incurred [Abstract]
Change in loss reserves	50,000,000		16,000,000
Increase (Decrease) in Severity, Pool Defaults [Member]
Losses incurred [Abstract]
Change in loss reserves	$ 6,000,000		$ 7,000,000

[1] At December 31, 2011 and 2010, the estimated reduction in loss reserves related to rescissions approximated $0.7 billion and $1.3 billion, respectively.

[2] 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.

[3] Rescissions did not have a significant impact on incurred losses in the three months ended March 31, 2012 or 2011.

[4] 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.

[5] Rescissions mitigated our paid losses by an estimated $0.1 billion in the three months ended March 31, 2012 and by an estimated $0.2 billion in the three months ended March 31, 2011, which excludes amounts that may have been applied to a deductible.

[6] At March 31, 2012 and 2011, the estimated reduction in loss reserves related to rescissions approximated $0.6 billion and $1.1 billion, respectively.