Balance Sheet Components - Schedule of Other Non-Current Liabilities and Deferred Credits (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Operating lease liabilities	$ 67,716	$ 65,565
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Finance lease liabilities	$ 48,815	$ 51,750
Deferred investment tax credits	29,866	30,444
Asset retirement obligations	17,194	20,338	$ 18,266	$ 17,482
Derivative liabilities	37,427	19,685
Other	13,981	13,407
Total	$ 214,999	$ 201,189