Asset Retirement Obligations (ARO) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligation, useful life	30 years
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at beginning of period	$ 31,053	$ 20,033
Additional obligations incurred	2,067	786
Accretion expense	489	313
Other	(15)	(9)
Balance at end of period	$ 33,594	$ 21,123