Subsidiary Guarantors - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Current assets
Cash	$ 5,478		$ 34,642
Accounts receivable, net
Oil and gas sales	29,136		26,568
Joint interest owners	17,533		5,267
Other	3,870		6,061
Commodity derivative assets	7,590		24,100
Other current assets	10,391	$ 11,198	2,684
Total current assets	73,998	101,524	99,322
Oil and gas properties, net, at cost under the successful efforts method	1,578,739	1,559,861	1,743,588
Other property, plant and equipment, net	2,565		2,996
Commodity derivative assets	1,608		34,744
Other assets	4,668		6,050
Total assets	1,661,578	1,739,706	1,886,700
Current liabilities
Trade accounts payable	67,550		36,527
Oil and gas sales payable	21,510		28,339
Accrued liabilities	24,472		25,707
Commodity derivative liabilities	15,696		14,650
Other current liabilities	3,224		2,584
Total current liabilities	132,452		107,807
Long-term debt	698,740		724,009
Deferred revenue	5,632		7,049
Commodity derivative liabilities	5,355		1,209
Asset retirement obligations	19,239		19,458
Liability under tax receivable agreement	55,096	14,140	43,045
Other liabilities	1,010		792
Deferred tax liabilities	2,732		2,905
Total liabilities	920,256	889,081	906,274
Mezzanine equity
Series A preferred stock, $0.001 par value; 1,839,995 shares issued and outstanding at September 30, 2017 and 1,840,000 shares issued and outstanding at December 31, 2016	89,413		88,975
Stockholders' / members' equity
Treasury stock, at cost: 22,602 shares at September 30, 2017 and December 31, 2016	(358)		(358)
Additional paid-in-capital	534,499		447,137
Retained earnings (deficit)	(181,226)	(114,454)	(8,652)
Stockholders' equity	353,013	362,675	438,214
Non-controlling interest	298,896	398,662	453,237
Total stockholders' equity	651,909	761,337	891,451
Total liabilities and stockholders' equity	1,661,578	$ 1,739,706	1,886,700
Class A common stock
Stockholders' / members' equity
Common stock	74		57
Class B common stock
Stockholders' / members' equity
Common stock	24		30
Eliminations
Accounts receivable, net
Intercompany receivable	(1,303,580)		(1,116,500)
Total current assets	(1,303,580)		(1,116,500)
Investment in subsidiaries	(591,264)		(984,600)
Total assets	(1,894,844)		(2,101,100)
Current liabilities
Intercompany payable	(1,303,580)		(1,116,500)
Total current liabilities	(1,303,580)		(1,116,500)
Total liabilities	(1,303,580)		(1,116,500)
Stockholders' / members' equity
Members' equity	(890,160)		(1,437,837)
Stockholders' equity	(890,160)		(1,437,837)
Non-controlling interest	298,896		453,237
Total stockholders' equity	(591,264)		(984,600)
Total liabilities and stockholders' equity	(1,894,844)		(2,101,100)
JEI (Parent)
Current assets
Cash	3,254		27,164
Accounts receivable, net
Other current assets	3,128
Intercompany receivable	199,444		15,666
Total current assets	205,826		42,830
Investment in subsidiaries	292,368		531,363
Total assets	498,194		574,193
Current liabilities
Accrued liabilities	33		3,874
Other current liabilities	639
Total current liabilities	672		3,874
Liability under tax receivable agreement	55,096		43,045
Deferred tax liabilities			85
Total liabilities	55,768		47,004
Mezzanine equity
Series A preferred stock, $0.001 par value; 1,839,995 shares issued and outstanding at September 30, 2017 and 1,840,000 shares issued and outstanding at December 31, 2016	89,413		88,975
Stockholders' / members' equity
Treasury stock, at cost: 22,602 shares at September 30, 2017 and December 31, 2016	(358)		(358)
Additional paid-in-capital	534,499		447,137
Retained earnings (deficit)	(181,226)		(8,652)
Stockholders' equity	353,013		438,214
Total stockholders' equity	353,013		438,214
Total liabilities and stockholders' equity	498,194		574,193
JEI (Parent) | Class A common stock
Stockholders' / members' equity
Common stock	74		57
JEI (Parent) | Class B common stock
Stockholders' / members' equity
Common stock	24		30
Issuers
Current assets
Cash	35		1,975
Accounts receivable, net
Other	2,162		5,434
Commodity derivative assets	7,590		24,100
Other current assets	431		422
Intercompany receivable	1,104,136		1,100,834
Total current assets	1,114,354		1,132,765
Commodity derivative assets	1,608		34,744
Other assets	3,707		5,265
Investment in subsidiaries	298,896		453,237
Total assets	1,418,565		1,626,011
Current liabilities
Trade accounts payable	59		13
Accrued liabilities	14,593		11,227
Commodity derivative liabilities	15,696		14,650
Other current liabilities	1,985		1,984
Total current liabilities	32,333		27,874
Long-term debt	698,740		724,009
Deferred revenue	5,632		7,049
Commodity derivative liabilities	5,355		1,209
Other liabilities	310		269
Deferred tax liabilities	2,732		2,820
Total liabilities	745,102		763,230
Stockholders' / members' equity
Members' equity	673,463		862,781
Stockholders' equity	673,463		862,781
Total stockholders' equity	673,463		862,781
Total liabilities and stockholders' equity	1,418,565		1,626,011
Guarantor Subsidiaries
Current assets
Cash	2,169		5,483
Accounts receivable, net
Oil and gas sales	29,136		26,568
Joint interest owners	17,533		5,267
Other	1,708		627
Other current assets	6,832		2,262
Total current assets	57,378		40,207
Oil and gas properties, net, at cost under the successful efforts method	1,578,739		1,743,588
Other property, plant and equipment, net	2,015		2,378
Other assets	961		785
Total assets	1,639,093		1,786,958
Current liabilities
Trade accounts payable	67,491		36,514
Oil and gas sales payable	21,510		28,339
Accrued liabilities	9,845		10,597
Other current liabilities	600		600
Intercompany payable	1,300,579		1,113,704
Total current liabilities	1,400,025		1,189,754
Asset retirement obligations	19,239		19,458
Other liabilities	700		523
Total liabilities	1,419,964		1,209,735
Stockholders' / members' equity
Members' equity	219,129		577,223
Stockholders' equity	219,129		577,223
Total stockholders' equity	219,129		577,223
Total liabilities and stockholders' equity	1,639,093		1,786,958
Non-Guarantor Subsidiaries
Current assets
Cash	20		20
Accounts receivable, net
Total current assets	20		20
Other property, plant and equipment, net	550		618
Total assets	570		638
Current liabilities
Accrued liabilities	1		9
Intercompany payable	3,001		2,796
Total current liabilities	3,002		2,805
Total liabilities	3,002		2,805
Stockholders' / members' equity
Members' equity	(2,432)		(2,167)
Stockholders' equity	(2,432)		(2,167)
Total stockholders' equity	(2,432)		(2,167)
Total liabilities and stockholders' equity	$ 570		$ 638