Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 70,881	$ 55,161
Other comprehensive earnings, tax effect, Pension and Postretirement Benefit Plans	(1,240)	(1,013)
Balance at end of period, Pension and Postretirement Benefit Plans	69,641	54,148
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	2,707	3,116
Other comprehensive earnings, tax effect, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(107)	(99)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	2,600	3,017
Balance at end of period, Net Non current Deferred Tax Assets	73,588	58,277
Other comprehensive earnings, tax effect, Net Non current Deferred Tax Assets	(1,347)	(1,112)
Balance at end of period, Net Non current Deferred Tax Assets	$ 72,241	$ 57,165