Commitments and Contingent Liabilities - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2010	Sep. 30, 2011	Mar. 31, 2011
Commitments and Contingencies Disclosure [Line Items]
Interest on undrawn retained asset account funds	18.00%
States involved in unclaimed property examination			32
Insurers requested to cross-check benefits		160