Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 54,148	$ 55,161
Other comprehensive earnings, tax effect, Pension and Postretirement Benefit Plans	(820)	(1,833)
Balance at end of period, Pension and Postretirement Benefit Plans	53,328	53,328
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	3,017	3,116
Other comprehensive earnings, tax effect, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(102)	(201)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	2,915	2,915
Balance at end of period, Net Noncurrent Deferred Tax Assets	57,165	58,277
Other comprehensive earnings, tax effect, Net Noncurrent Deferred Tax Assets	(922)	(2,034)
Balance at end of period	$ 56,243	$ 56,243