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	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Staff reductions and Cost Saving Initiatives	$ 0	$ 247
RSU [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Staff reductions and Cost Saving Initiatives	$ 0	$ 9,099