Capital Requirements (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) jurisdiction		Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Sep. 30, 2012
Statutory Capital [Abstract]
Percentage of surplus as regards policyholders (in hundredths)	15.00%				10.00%
Statutory deferred tax assets admitted	$ 205,000		$ 138,000	$ 138,000
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%
Net (loss) income	$ (72,767)	[1]	13,203	(8,046)
Surplus	1,608,214	[1]	1,585,164	1,584,121
Contingency Reserve	$ 826,706		318,247	18,558
Statutory capital requirements [Abstract]
Number of jurisdictions with risk-to-capital requirements | jurisdiction	16
Maximum permitted risk-to-capital ratio commonly applied	25 to 1
Risk-to-capital ratio on a combined basis at end of period	13.6 to 1
Risk-to-capital ratio on combined insurance operations	13.6
Maximum
Statutory capital requirements [Abstract]
Risk to capital ratio	25
Mortgage Guaranty Insurance Corporation
Related Party Transaction [Line Items]
Loss ratio	37.00%
Surplus contributions made to subsidiary by the parent company	$ 0		0	800,000
Dividends paid to the parent company	$ 0		0	0
Statutory capital requirements [Abstract]
Risk to capital ratio	12.1
Risk to capital ratio at end of period	12.1 to 1
Amount of policyholders position above or below required MPP	$ 1,200,000
Amount of required MPP	1,100,000
Other Insurance Subsidiaries
Related Party Transaction [Line Items]
Surplus contributions made to subsidiary by the parent company	0		0	0
Dividends paid to the parent company	$ 38,500		$ 0	$ 0

[1] The dissolution of an MGIC non-insurance subsidiary in 2015 had no impact on statutory surplus as the equity value of the investment was fully reflected in surplus as an unrealized loss prior to 2015.