Leases - Lease costs (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended |
---|---|---|
Jun. 30, 2019 |
Jun. 30, 2019 |
|
Operating Leased Assets [Line Items] | ||
Operating lease cost | $ 18,477 | $ 22,825 |
Variable lease cost | 41,889 | 59,180 |
Short-term lease cost | 1,812 | 2,665 |
Total lease cost | 62,178 | 84,670 |
Purchased Power Lease Contracts | ||
Operating Leased Assets [Line Items] | ||
Operating lease cost | 14,063 | 14,063 |
Variable lease cost | 41,529 | 58,820 |
Short-term lease cost | 0 | 0 |
Total lease cost | 55,592 | 72,883 |
Land, Property & Equipment Leases | ||
Operating Leased Assets [Line Items] | ||
Operating lease cost | 4,414 | 8,762 |
Variable lease cost | 360 | 360 |
Short-term lease cost | 1,812 | 2,665 |
Total lease cost | $ 6,586 | $ 11,787 |