Balance Sheet Components - Customer Financing Leases Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2019		Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Total minimum lease payments to be received	$ 76,886						$ 100,816
Less: Amounts representing estimated executing costs	(19,931)						(25,180)
Net present value of minimum lease payments to be received	56,955						75,636
Estimated residual value of leased assets	890						1,051
Less: Unearned income	(1,990)						(4,011)
Net investment in sales-type financing leases	55,855						72,676
Less: Current portion	(5,108)	[1]	$ (5,919)	$ (5,817)	$ (5,717)	$ (5,594)	(5,594)	[1]	$ (5,496)	$ (5,398)	$ (5,303)
Non-current portion of investment in sales-type financing leases	$ 50,747	[1]	$ 62,615	$ 64,146	$ 65,620	$ 67,082	$ 67,082	[1]	$ 68,535	$ 69,963	$ 71,337

[1] We have variable interest entities which represent a portion of the consolidated balances are recorded within these financial statement line items in the Consolidated Balance Sheets (see Note 13, Power Purchase Agreement Programs).