Fair Value Measurements (Narrative) (Detail)	9 Months Ended
	Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Weighted-average risk grade of loans underlying interest rate swaps measured at fair value	11.1
Weighted-average loss severity	10.00%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Default on the interest rate swaps, loss severity percentage	50.00%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Default on the interest rate swaps, weighted average loss severity percentage	20.10%