Summary of Net Periodic Pension Cost (Credit) and Other Amounts Recognized in Other Comprehensive Loss (Income) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 889	$ 3,059	$ 1,864
Interest cost	712	1,225	1,479
Expected return on assets	(2,315)	(3,038)	(4,243)
Prior service costs	440	649	695
Amortization of loss	48
Settlement loss	1,162	3,698	2,791
One-time charge in connection with an increase in benefits for certain participants		1,401
Curtailment charge	2,063	2,173	1,346
Net periodic pension cost	2,999	9,167	3,932
Other changes in Plan Assets and Obligations recognized in Other Comprehensive Income:
Prior service cost	(2,503)	(769)	(282)
Loss (gain)	1,275	(2,531)	(2,368)
Total other comprehensive income	(1,228)	(3,300)	(2,650)
Total net periodic pension cost and other comprehensive income	$ 1,771	$ 5,867	$ 1,282