Summary Of Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011 Unit	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 Unit State	Dec. 31, 2011 Location Unit	Dec. 31, 2010
Summary Of Significant Accounting Policies [Line Items]
Minimum retention period for employees									60 days
Number of divisions approved by restructuring plan to consolidate					8					8
Number of operating regions										4
Restructuring charges	$ 539,000	$ 3,056,000	$ 4,551,000	$ 1,411,000	$ 9,995,000	$ 839,000	$ 1,831,000	$ 306,000	$ 9,557,000	$ 12,971,000	$ 0
Restructuring charges paid									8,038,000
Legal, professional and other costs incurred in response to unsolicited tender offer	49,000	1,206,000	32,060,000	10,065,000	2,227,000				43,380,000	2,227,000	0
Legal, professional and other costs paid									43,107,000
Period considered to treat investments as cash equivalent									Three months or less
Accounts and notes receivable, credit period									30 days
Bad debt expense									2,505,000	1,644,000	3,100,000
Write-offs of accounts receivables									2,805,000	2,651,000	4,317,000
Financing receivable	8,609,000				7,471,000				8,609,000	7,471,000
Related party receivable amount due in 2014	1,550,000				1,550,000				1,550,000	1,550,000
Capitalized software costs	10,855,000				12,910,000				10,855,000	12,910,000
Capitalized software costs during the year									408,000	3,746,000	1,167,000
Depreciated capitalized software costs									2,463,000	2,520,000	2,895,000
Total gain (losses) of the Rabbi Trust investment									8,564,000	(3,292,000)
Gains (losses) related to investments still held by Rabbi Trust									9,012,000	(3,370,000)
Goodwill	3,086,716,000				3,086,716,000				3,086,716,000	3,086,716,000	3,097,016,000
Percentage of goodwill in total assets	38.00%				38.00%				38.00%	38.00%
Number of operating segments									4
Number of reporting units based on geographic location									19
Goodwill impairment charges									0	0	0
Percentage of net property, plant & equipment in total assets	39.00%								39.00%
Percentage of other intangible assets, net in total assets	9.00%								9.00%
Loss on impairment of long-lived assets									2,034,000		3,936,000
Stripping costs included in cost of inventory	37,875,000				40,049,000				37,875,000	40,049,000	40,842,000
Pre-production stripping costs capitalized	18,887,000				17,860,000				18,887,000	17,860,000
Research and development costs									0	1,109,000	1,582,000
Excess tax benefits from share-based compensation									267,000	121,000	808,000
Carrying value of reclamation obligations	150,072,000				153,979,000				150,072,000	153,979,000	162,730,000
Spread between the amount accrued and the maximum environmental loss									3,940,000
Maximum self-insurance coverage per occurrence for losses related to workers' compensation	2,000,000								2,000,000
Maximum self-insurance coverage per occurrence for automotive and general/product liability	$ 3,000,000								$ 3,000,000
Accounting Standards Codification Topic 740 - Income Taxes recognition threshold for uncertain tax positions									50.00%
Antidilutive common stock equivalents									617,000	304,000	415,000
Basis of determining impairment test									a likelihood of more than 50%
Machinery and Equipment | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated service life									3 years
Machinery and Equipment | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated service life									30 years
Building | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated service life									10 years
Building | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated service life									20 years
Land Improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated service life									7 years
Land Improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated service life									20 years