Earnings Per Share - Comparison of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net earnings (loss) from continuing operations									$ 902,175	$ (162,354)	$ 300,465
Net earnings from discontinued operations, net of income taxes									0	0	10,993
NET EARNINGS (LOSS) ATTRIBUTABLE TO ENSTAR GROUP LIMITED ORDINARY SHAREHOLDERS	$ 193,839	$ 117,743	$ 231,842	$ 358,751	$ (113,423)	$ (15,965)	$ 8,244	$ (41,210)	$ 902,175	$ (162,354)	$ 311,458
Denominator:
Weighted-average ordinary shares outstanding — basic (shares)									21,482,617	20,698,310	19,388,621
Effect of dilutive securities:
Share-based compensation plans (shares)									227,878	129,746	62,732
Warrants (shares)									64,571	76,120	76,238
Weighted-average ordinary shares outstanding - diluted (shares)									21,775,066	20,904,176	19,527,591
Basic:
Net earnings (loss) from continuing operations (dollars per share)									$ 42.00	$ (7.84)	$ 15.50
Net earnings from discontinued operations (dollars per share)									0	0	0.56
Net earnings (loss) per ordinary share (dollars per share)	$ 9.02	$ 5.48	$ 10.79	$ 16.71	$ (5.29)	$ (0.74)	$ 0.40	$ (2.12)	42.00	(7.84)	16.06
Diluted:
Net earnings (loss) from continuing operations (dollars per share)									41.43	(7.84)	15.39
Net earnings from discontinued operations, net of income taxes (dollars per share)									0	0	0.56
Net earnings (loss) per ordinary share (dollars per share)	$ 8.89	$ 5.42	$ 10.70	$ 16.57	$ (5.29)	$ (0.74)	$ 0.40	$ (2.12)	$ 41.43	$ (7.84)	$ 15.95