Significant Accounting Policies - Schedule of Cumulative Impact of Adoption of ASC 842 Using Retrospective Approach (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Long-term right-of-use assets	$ 127,861
Total assets	1,834,368		$ 1,733,288
Lease liabilities (current)	11,261
Deferred gain on sale of liquids gathering system			94,636
Long-term lease liabilities	116,613
Total liabilities	2,748,371		2,781,910
Retained earnings (loss)	(3,052,524)		(3,186,016)
Total stockholders' equity (deficit)	(914,003)		(1,048,622)	$ (1,096,734)	$ (1,154,636)
Total liabilities and stockholders' equity (deficit)	$ 1,834,368		$ 1,733,288
ASC 842
Significant Accounting Policies [Line Items]
Long-term right-of-use assets		$ 130,649
Total assets		1,863,937
Lease liabilities (current)		11,141
Long-term lease liabilities		121,326
Total liabilities		2,819,741
Retained earnings (loss)		(3,093,198)
Total stockholders' equity (deficit)		(955,804)
Total liabilities and stockholders' equity (deficit)		1,863,937
ASC 842 | Impact of ASC 842
Significant Accounting Policies [Line Items]
Long-term right-of-use assets		130,649
Total assets		130,649
Lease liabilities (current)		11,141
Deferred gain on sale of liquids gathering system		(94,636)
Long-term lease liabilities		121,326
Total liabilities		37,831
Retained earnings (loss)		92,818
Total stockholders' equity (deficit)		92,818
Total liabilities and stockholders' equity (deficit)		$ 130,649