Incentive Plans - Summary of Impact of Share-Based Incentive Plans on Compensation and Benefits Expense (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cost Saving Initiatives	$ 4,455
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cost Saving Initiatives	$ 233