Cumulative Other Comprehensive Loss - Cumulative Other Comprehensive Loss in Accompanying Consolidated Statements of Equity (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (530,602)
Ending balance	(509,767)	$ (530,602)
Cumulative Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	9,059	59,660
Other comprehensive income (loss) before reclassifications	(31,093)	(50,601)
Net current-period other comprehensive income (loss)	(31,093)	(50,601)
Ending balance	(22,034)	9,059
Changes in the Fair Value of Derivatives and Unrealized Gains (Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	4,762	1,615
Other comprehensive income (loss) before reclassifications	6,971	5,626
Amount reclassified from accumulated other comprehensive loss	(8,279)	(2,479)
Net current-period other comprehensive income (loss)	(1,308)	3,147
Ending balance	3,454	4,762
Unrecognized Postretirement Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(544,423)	(471,295)
Other comprehensive income (loss) before reclassifications	23,263	(96,737)
Amount reclassified from accumulated other comprehensive loss	29,973	23,609
Net current-period other comprehensive income (loss)	53,236	(73,128)
Ending balance	(491,187)	(544,423)
Cumulative Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(530,602)	(410,020)
Other comprehensive income (loss) before reclassifications	(18,482)	(141,712)
Amount reclassified from accumulated other comprehensive loss	39,317	21,130
Net current-period other comprehensive income (loss)	20,835	(120,582)
Ending balance	$ (509,767)	$ (530,602)