v3.19.3.a.u2

PPAs and other definite-lived intangible assets and liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Components of intangible assets |  |
Assets, gross balance at the end of the period | $ 365.6 | $ 362.7
Less: accumulated amortization | (221.3) | (192.6)
Assets, net balance at the end of the period | 144.3 | 170.1
Liabilities, gross balances at the end of the period | (40.7) | (41.3)
Less: accumulated amortization | 20.9 | 20.1
Liabilities, net balance at the end of the period | (19.8) | (21.2)
Power Purchase Agreements |  |
Components of intangible assets |  |
Assets, gross balance at the end of the period | 365.6 | 362.7
Less: accumulated amortization | (221.3) | (192.6)
Assets, net balance at the end of the period | 144.3 | 170.1
Liabilities, gross balances at the end of the period | (28.1) | (28.7)
Less: accumulated amortization | 14.4 | 14.0
Liabilities, net balance at the end of the period | (13.7) | (14.7)
Fuel Supply Agreements |  |
Components of intangible assets |  |
Liabilities, gross balances at the end of the period | (12.6) | (12.6)
Less: accumulated amortization | 6.5 | 6.1
Liabilities, net balance at the end of the period | $ (6.1) | $ (6.5)

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- Definition Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 + Details
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