Statutory Capital (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 Jurisdiction	Dec. 31, 2012	Dec. 31, 2011
Statutory Capital [Abstract]
Percentage of premiums earned required to be maintained as contingency loss reserves (in hundredths)	50.00%
Period that contingency loss reserves must be held (in years)	10 years
Percentage of net premiums earned that incurred losses must exceed to enable early withdrawals from contingency loss reserves (in hundredths)	35.00%
Percentage of new insurance written in jurisdictions with risk-to-capital requirements (in hundredths)	50.00%
Percentage of surplus as regards policyholders (in hundredths)	10.00%
Statutory deferred tax assets admitted	$ 138,000,000	$ 63,000,000
Net (loss) income	(8,046,000)	(902,878,000)	(436,277,000)
Surplus	1,584,121,000	748,592,000	1,657,349,000
Contingency Reserve	18,558,000	6,430,000	4,104,000
Statutory capital requirements [Abstract]
Risk-to-capital ratio at end of period, excluding the effects of the Addendum	19.2 to 1
Maximum permitted risk-to-capital ratio commonly applied	25 to 1
Risk-to-capital ratio on a combined basis at end of period	18.4 to 1
Number of jurisdictions with risk-to-capital requirements	16
Contribution to subsidiary	800,000,000
Mortgage Guaranty Insurance Corporation [Member]
Related Party Transaction [Line Items]
Surplus contributions made to subsidiary by the parent company	800,000,000	100,000,000	200,000,000
Dividends paid by MGIC to the parent company	0	0	0
Statutory capital requirements [Abstract]
Risk to capital ratio at end of period	15.8 to 1
Amount of policyholders position above or below required MPP	454,000,000
Amount of required MPP	1,000,000,000
MGIC Indemnity Corporation [Member]
Related Party Transaction [Line Items]
Statutory capital of subsidiary	458,000,000
Risk in force, net of reinsurance, of subsidiary	600,000,000
Other Insurance Subsidiaries [Member]
Related Party Transaction [Line Items]
Surplus contributions made to subsidiary by the parent company	$ 0	$ 0	$ 0