Reconciliation of Beginning and Ending Balance for Assets and Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balances-Liabilities	$ 16,576	$ 15,970
Total gain (loss) included in accumulated other comprehensive loss, Liabilities	(1,576)	1,736
Total gain included in earnings, Liabilities	(808)	(1,130)
Ending balance - Liabilities	14,192	16,576
Beginning balances, Assets		8,955
Total gain (loss) included in accumulated other comprehensive loss		(8,955)
Total gain included in earnings