Intangible Assets, Intangible Liabilities, and Goodwill - Intangible Assets Subject to Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 259,698	$ 160,798
Intangible liabilities, gross	38,300	0
Net intangible assets carrying amount	221,398	160,798
Accumulated amortization	(115,167)	(76,491)
Net intangible assets subject to amortization	106,231	84,307
Power supply agreements
Finite-Lived Intangible Assets [Line Items]
Intangible liabilities, gross	14,200	0
LTSA
Finite-Lived Intangible Assets [Line Items]
Intangible liabilities, gross	$ 24,100	$ 0