Organization and Significant Accounting Policies - Narrative (Detail) - USD ($) $ in Billions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Minimum
Schedule Of Significant Accounting Policies [Line Items]
Senior secured loans, maturity period	3 years
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Senior secured loans, maturity period	8 years
Interest Rate Swaps
Schedule Of Significant Accounting Policies [Line Items]
Cash on margin with counterparty to interest rate swaps	$ 2.2	$ 1.6