Derivative Instruments - Narrative (Detail) (USD $)	Jun. 30, 2011	Jun. 30, 2010
Derivative [Line Items]
Interest rate swaps - weighted average pay rate, percentage	2.79%	3.48%
Interest rate swaps - weighted average receive rate, percentage	0.21%	0.38%
Gross Unrealized Losses and Unrealized Gains on Interest Rate Swaps:
Interest rate swaps, gross unrealized loss	$ 1,000,000,000	$ 820,000,000
Interest rate swaps, notional amount related to gross unrealized loss	32,400,000,000	23,200,000,000
Interest rate swaps, gross unrealized gain	23,200,000	68,200,000
Interest rate swaps, notional amount related to gross unrealized gain	$ 3,200,000,000	$ 3,900,000,000