Employee Benefits - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
2006 Equity Incentive Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Total unrecognized compensation cost related to non-vested share awards	$ 4.0	$ 6.8
Total unrecognized compensation cost related to non-vested awards, period of recognition	1 year 7 months 6 days
Compensation costs recognized in earnings	0.7	0.8
2011-2015 Annual Incentive Compensation Program [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Accrued expense	5.2	2.1
Enstar Group Limited Employee Share Purchase Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Compensation costs recognized in earnings	$ 0.1	$ 0.1
Shares issued to employees	1,559	1,308
Employees [Member] | 2006 Equity Incentive Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Shares awarded to employees