CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury	Noncontrolling Interest	Total
Balance at Dec. 31, 2009	$ 3,461	$ 833,494	$ 1,414,327	$ 84,276	$ (4,333)	$ 9,756	$ 2,340,981
Balance, shares at Dec. 31, 2009	346,081
Comprehensive loss:
Net income (loss)			604,118			(285)	603,833
Other comprehensive income (loss)				(301)			(301)
Total comprehensive income (loss)						(285)	603,532
Comprehensive income (loss) attributable to Southwestern Energy							603,817
Stock-based compensation		16,569					16,569
Exercise of stock options, shares	1,293
Exercise of stock options	12	3,885					3,897
Issuance of restricted stock, shares	392
Issuance of restricted stock	4	(4)
Cancellation of restricted stock, shares	(30)
Tax withholding - stock compensation, shares	(3)
Tax withholding - stock compensation		(112)					(112)
Issuance of stock awards, shares	1
Issuance of stock awards		37					37
Treasury stock - non-qualified plan		771			889		1,660
Distributions to noncontrolling interest in partnership						(188)	(188)
Purchase of noncontrolling interest in partnership		7,783				(9,283)	(1,500)
Balance at Dec. 31, 2010	3,477	862,423	2,018,445	83,975	(3,444)		2,964,876
Balance, shares at Dec. 31, 2010	347,734
Comprehensive loss:
Net income (loss)			637,769				637,769
Other comprehensive income (loss)				324,453			324,453
Total comprehensive income (loss)							962,222
Comprehensive income (loss) attributable to Southwestern Energy							962,222
Tax benefit for stock-based compensation		14,626					14,626
Stock-based compensation		19,036					19,036
Exercise of stock options, shares	851
Exercise of stock options	9	6,403					6,412
Issuance of restricted stock, shares	532
Issuance of restricted stock	5	(5)
Cancellation of restricted stock, shares	(52)
Cancellation of restricted stock		1					1
Tax withholding - stock compensation, shares	(7)
Tax withholding - stock compensation		(262)					(262)
Issuance of stock awards, shares	1
Issuance of stock awards		42					42
Treasury stock - non-qualified plan		1,135			1,216		2,351
Balance at Dec. 31, 2011	3,491	903,399	2,656,214	408,428	(2,228)		3,969,304
Balance, shares at Dec. 31, 2011	349,059
Comprehensive loss:
Net income (loss)			(707,064)				(707,064)
Other comprehensive income (loss)				(258,624)			(258,624)
Total comprehensive income (loss)							(965,688)
Comprehensive income (loss) attributable to Southwestern Energy							(965,688)
Stock-based compensation		22,212					22,212
Exercise of stock options, shares	1,607
Exercise of stock options	16	9,168					9,184
Issuance of restricted stock, shares	539
Issuance of restricted stock	5	(5)
Cancellation of restricted stock, shares	(95)
Cancellation of restricted stock	(1)	1
Tax withholding - stock compensation, shares	(11)
Tax withholding - stock compensation		(393)					(393)
Issuance of stock awards, shares	1
Issuance of stock awards		44					44
Treasury stock - non-qualified plan		513			696		1,209
Balance at Dec. 31, 2012	$ 3,511	$ 934,939	$ 1,949,150	$ 149,804	$ (1,532)		$ 3,035,872
Balance, shares at Dec. 31, 2012	351,100