Reconciliation of Beginning and Ending Balances for Assets Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 1,820	$ 1,547
Transfers into Level 3
Total gains/ (losses) included in:
Net loss
Other comprehensive income	(123)	150
Purchases, sales, issuances and settlements, net	(4)	(4)
Ending balance	$ 1,693	$ 1,693