Nature of Business and Basis of Presentation (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Nature of Business and Basis of Presentation [Abstract]
(Increase) decrease in restricted cash		$ 42,900,000	$ (60,300,000)	$ (237,000)	$ 60,333,000
PMIERs effective days after publication	180 days
Mortgage Insurers transition period	2 years
Period for submission of transition plan to GSE	90 days
Holding company cash and investments	515,000,000			515,000,000
Assets of regulated insurance affiliates of MGIC	100,000,000			100,000,000
Restricted cash and cash equivalents	$ 17,203,000	$ 17,440,000		$ 17,203,000