Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Number of investment funds		3
Unfunded commitments		$ 2.4
Fixed maturities and cash equivalents on deposit with various insurance departments at fair value and amortized cost		5.3
Cash equivalents on deposit with another insurance company at fair value and amortized cost		9.4
Collateralized Mortgage Obligations [Member] | Non-Agency Backed - Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Non credit other than temporary impairment for securities	1.0	0.9	1.0
Collateralized Mortgage Obligations [Member] | Non-Agency Backed - Commercial [Member]
Schedule of Available-for-sale Securities [Line Items]
Non credit other than temporary impairment for securities	$ 0.2	$ 0.2	$ 0.2