Acquisitions and Discontinued Operations - Additional Information (Detail) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	6 Months Ended	12 Months Ended					12 Months Ended
	Jun. 30, 2011 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2013 GBP (£)	Apr. 20, 2011 GBP (£)	Dec. 31, 2012 Citizens Management, Inc. USD ($)	Dec. 31, 2013 Discontinued Accident And Health Insurance Business USD ($)	Dec. 31, 2012 Discontinued Accident And Health Insurance Business USD ($)
Significant Acquisitions and Disposals [Line Items]
Per share amount received by shareholders, pence						£ 0.533	£ 0.533
Business acquisition, purchase price, settlement loss		$ 11.3			$ 11.3
Gain (loss) on foreign exchange		6.4			6.4
Acquisition costs	11.7		0.1	2.6	16.4
Current exchange rate between GBP and US dollars		1.60
Assets of discontinued operations			114.9	130.5					66.6	72.9
Liabilities of discontinued operations			121.1	126.3					51.3	52.5
Gain from insurance settlement			5.8
Gain on discontinued operations, after taxes				0.7	5.2			10.8
Contribution to charitable foundation that offset gain from disposal of discontinued operation				$ 1.7