Assets Held-for-Sale and Discontinued Operations Disc Ops (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income (loss) from discontinued operations
Income (loss) from Oil and Gas discontinued operations, net of tax	$ (27,134)	$ (12,187)	$ (43,077)	$ (14,097)
Litigation amount as per judgment			16,500
Gas transport and processing
Contracts for gas transport and processing
Contractual Obligation	13,000		13,000		$ 17,200
Gas transport and processing | Disposal Group, Held-for-sale, Not Discontinued Operations
Contracts for gas transport and processing
Recorded contractual commitments			9,900		12,500
Gas transport and processing | Disposal Group, Held-for-sale, Not Discontinued Operations | Accrued liabilities
Contracts for gas transport and processing
Recorded contractual commitments			6,100		$ 5,500
Oil and Gas
Income (loss) from discontinued operations
Impairment charge	35,300	15,400	35,300	15,400
Oil and Gas | Discontinued Operations, Held-for-sale or Disposed of by Sale
Income (loss) from discontinued operations
Operating revenues	1,077	688	5,171	1,449
Income (loss) from discontinued operations	(991)	(836)	(1,561)	(3,501)
Less: Impairment charges or other (gains) and losses on sale of wholly owned assets (2)	34,469	15,392	51,028	15,388
Less: Income tax expense (benefit)	(8,326)	(4,041)	(9,512)	(4,792)
Income (loss) from Oil and Gas discontinued operations, net of tax	$ (27,134)	$ (12,187)	$ (43,077)	$ (14,097)