Summary of Fair Value Transfers Between Level I and Level II (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers from Level I into Level II			$ 75,134	[1]
Transfers from Level II into Level I	$ 18,029	[2]

[1] Transfers out of Level I represent those financial instruments for which restrictions exist and adjustments were made to an otherwise observable price to reflect fair value at the reporting date.

[2] Transfers into Level I represent those financial instruments for which an unadjusted quoted price in an active market became available for the identical asset.