Capitalized Costs and Accumulated Depreciation Depletion and Amortization

9 Months Ended

Sep. 30, 2011

Extractive Industries [Abstract]

CAPITALIZED COSTS AND ACCUMULATED DEPRECIATION, DEPLETION AND AMORTIZATION

(17) CAPITALIZED COSTS AND ACCUMULATED DEPRECIATION, DEPLETION AND AMORTIZATION^(a)

	September 30,
	2011			December 31, 2010
	(in thousands)
Natural gas and oil properties:
Properties subject to depletion	$	5,689,410		$	4,742,248
Unproved properties		730,620			648,143
Total		6,420,030			5,390,391
Accumulated depreciation, depletion and amortization		(1,573,195	)		(1,306,378	)
Net capitalized costs	$	4,846,835		$	4,084,013

^(a) Includes capitalized asset retirement costs and associated accumulated amortization.