Contingencies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Mar. 31, 2015
Loss Contingencies [Line Items]
Number of plaintiffs ordered to trial				14
Legacy tax liabilities	$ 6.4	$ 6.4	$ 19.2
Abu Dhabi Commercial Bank Litigation [Member]
Loss Contingencies [Line Items]
Number of plaintiffs dismissed by court	4
Number of plaintiffs	11
Number of plaintiffs granted	2
Number of plaintiffs filed motions for reconsideration	3
Total compensatory damages value	$ 76.0
King County, Washington and Iowa Student Loan Liquidity Corporation [Member]
Loss Contingencies [Line Items]
Number of plaintiffs	2
CalPERS [Member]
Loss Contingencies [Line Items]
Unrealized losses claimed by the plaintiff	$ 779.0
CalPERS [Member] | Damages Sought for All Plaintiffs [Member]
Loss Contingencies [Line Items]
Total compensatory damages value	1,300.0
Pursuit Partners LLC [Member] | Damages Sought for All Plaintiffs [Member]
Loss Contingencies [Line Items]
Total compensatory damages value	$ 44.0