Accrued Workers' Compensation (Tables)

12 Months Ended

Dec. 31, 2011

Accrued Workers Compensation [Line Items]

Workers' Compensation Expense

	Year Ended December 31
	2011	2010	2009
	(In thousands)
Self-insured occupational disease benefits:
Service cost	$    2,059	$       727	$        531
Interest cost	1,799	675	558
Net amortization	(493)	(1,860)	(2,879)
Total occupational disease	3,365	(458)	(1,790)
Traumatic injury claims and assessments	16,979	9,263	8,904
Total workers' compensation expense	$  20,344	$    8,805	$     7,114

Workers' Compensation [Member]

Accrued Workers Compensation [Line Items]

Schedule Of Changes in Projected Benefit Obligations

	December 31
	2011	2010
	(In thousands)
Beginning of year obligation	$  17,412	$  9,702
Service cost	2,059	727
Interest cost	1,799	675
Actuarial loss	7,081	6,993
Benefit and administrative payments	(1,097)	(685)
Acquisition of ICG	26,930	—
Net obligation at end of year	$  54,184	$ 17,412

Schedule of Occupational Disease Obligation

	Year Ended December 31
	2011	2010	2009
Weighted average assumptions:
Discount rate	5.10%	5.96%	6.11%
Cost escalation rate	3.00%	3.00%	3.00%

Schedule Of Amounts Recognized In Balance Sheet

	December 31
	2011	2010
	(In thousands)
Occupational disease costs	$  54,184	$  17,412
Traumatic and other workers' compensation claims	29,430	24,537
Total obligations	83,614	41,949
Less amount included in accrued expenses	11,666	6,659
Noncurrent obligations	$  71,948	$  35,290