Assets Held-for-Sale and Discontinued Operations Disc Ops (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Income (loss) from discontinued operations
Income (loss) from Oil and Gas discontinued operations, net of tax	$ (15,504)	$ (984)	$ (15,943)	$ (1,910)
Litigation amount as per judgment			16,500
Gas transport and processing
Contracts for gas transport and processing
Contractual Obligation	14,300		14,300		$ 17,200
Gas transport and processing | Disposal Group, Held-for-sale, Not Discontinued Operations
Contracts for gas transport and processing
Recorded contractual commitments			10,700		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			5,800		$ 5,500
Oil and Gas | Discontinued Operations, Held-for-sale or Disposed of by Sale
Income (loss) from discontinued operations
Operating revenues	2,060	384	4,094	761
Income (loss) from discontinued operations	20	(1,335)	(570)	(2,661)
Less: Impairment charges or other (gains) and losses on sale of wholly owned assets (2)	16,539		16,559
Less: Income tax expense (benefit)	(1,015)	(351)	(1,186)	(751)
Income (loss) from Oil and Gas discontinued operations, net of tax	$ (15,504)	$ (984)	$ (15,943)	$ (1,910)