Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 28,441	$ 31,610	$ 23,473	$ 245,979
Accounts receivable, net of allowance for doubtful accounts of $1,195 and $1,320 at December 31, 2016 and December 31, 2017, respectively	34,896	29,682
Accrued revenue	300,122	261,960
Derivative instruments	460,685	73,022
Other current assets	8,943	6,313
Total current assets	833,087	402,587
Natural gas properties, at cost (successful efforts method):
Unproved properties	2,266,673	2,331,173
Proved properties	11,096,462	9,549,671
Water handling and treatment systems	946,670	744,682
Gathering systems and facilities	2,050,490	1,723,768
Other property and equipment	57,429	41,231
Property and equipment, gross	16,417,724	14,390,525
Less accumulated depletion, depreciation, and amortization	(3,182,171)	(2,363,778)
Property and equipment, net	13,235,553	12,026,747
Derivative instruments	841,257	1,731,063
Investments in unconsolidated affiliates	303,302	68,299
Other assets	48,291	26,854
Total assets	15,261,490	14,255,550
Current liabilities:
Accounts payable	62,982	38,627
Accrued liabilities	443,225	393,803
Revenue distributions payable	209,617	163,989
Derivative instruments	28,476	203,635
Other current liabilities	17,796	17,334
Total current liabilities	762,096	817,388
Long-term liabilities:
Long-term debt	4,800,090	4,703,973
Deferred income tax liability	779,645	950,217
Derivative instruments	207	234
Other liabilities	43,316	55,160
Total liabilities	6,385,354	6,526,972
Equity:
Common stock, $0.01 par value; authorized - 1,000,000 shares; 314,877 shares and 316,379 shares issued and outstanding at December 31, 2016 and 2017, respectively	3,164	3,149
Additional paid-in capital	6,570,952	5,299,481
Accumulated earnings	1,575,065	959,995
Total stockholders' equity	8,149,181	6,262,625
Noncontrolling interest in consolidated subsidiary	726,955	1,465,953
Total equity	8,876,136	7,728,578	$ 7,286,678	$ 5,473,830
Total liabilities and equity	$ 15,261,490	$ 14,255,550