Assets Held-for-Sale and Discontinued Operations Disc Ops (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Income (loss) from discontinued operations
Income (loss) from discontinued operations, net of tax	$ (12,187)	$ (45,275)	$ (14,097)	$ (41,067)
Impairment charge	15,400	15,400	51,000	51,000
Impairment of note receivable		4,000		4,000
Gas transport and processing
Contracts for gas transport and processing
Contractual Obligation	19,400		19,400		$ 23,300
Gas transport and processing | Disposal Group, Held-for-sale, Not Discontinued Operations
Contracts for gas transport and processing
Recorded contractual commitments			13,900		16,100
Gas transport and processing | Disposal Group, Held-for-sale, Not Discontinued Operations | Accrued liabilities
Contracts for gas transport and processing
Recorded contractual commitments			5,500		$ 5,200
Oil and Gas | Discontinued Operations, Held-for-sale or Disposed of by Sale
Income (loss) from discontinued operations
Operating revenues	688	432	1,449	2,737
Income (loss) from discontinued operations	(836)	(1,388)	(3,501)	(3,903)
Less: Impairment charges or other (gains) and losses on sale of wholly owned assets and obligations	15,392	55,044	15,388	56,075
Less: Income tax expense (benefit)	(4,041)	(11,157)	(4,792)	(18,911)
Income (loss) from discontinued operations, net of tax	$ (12,187)	$ (45,275)	$ (14,097)	$ (41,067)