XML 16 R54.htm IDEA: XBRL DOCUMENT

Summary of Depreciation, Depletion, Amortization and Impairment Expense Related to Property and Equipment and Intangible Assets (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant, and Equipment Disclosure [Line Items]
Depreciation and impairment expense	$ 419,200,000	$ 322,300,000	$ 280,600,000
Amortization expense	4,100,000	1,000,000
Depletion expense	14,000,000	10,200,000	9,200,000
Total	$ 437,279,000	$ 333,493,000	$ 289,847,000

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References+ Details