Statutory Capital (Details) (USD $)	1 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
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 surplus as regards policyholders (in hundredths)		10.00%
Statutory deferred tax assets admitted		$ 138,000,000	$ 138,000,000	$ 63,000,000
Net (loss) income		13,203,000	(8,046,000)	(902,878,000)
Surplus		1,585,164,000	1,584,121,000	748,592,000
Contingency Reserve		318,247,000	18,558,000	6,430,000
Statutory capital requirements [Abstract]
Maximum permitted risk-to-capital ratio commonly applied		25 to 1
Risk-to-capital ratio on a combined basis at end of period		16.4 to 1
Number of jurisdictions with risk-to-capital requirements		16
Mortgage Guaranty Insurance Corporation [Member]
Related Party Transaction [Line Items]
Surplus contributions made to subsidiary by the parent company	800,000,000	0	800,000,000	100,000,000
Dividends paid by MGIC to the parent company		0	0	0
Statutory capital requirements [Abstract]
Risk to capital ratio at end of period		14.6 to 1
Amount of policyholders position above or below required MPP		673,000,000
Amount of required MPP		1,000,000,000
Other Insurance Subsidiaries [Member]
Related Party Transaction [Line Items]
Surplus contributions made to subsidiary by the parent company		$ 0	$ 0	$ 0