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Accumulated other comprehensive income (loss) (Policies) | 12 Months Ended
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Dec. 31, 2020
Equity [Abstract] |
Accumulated other comprehensive income (loss) (Policy) | The Company's accumulated other comprehensive income (loss) is comprised of losses on derivative instruments qualifying as hedges, postretirement liability adjustments and gain (loss) on available-for-sale investments.

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- Definition Disclosure of accounting policy for comprehensive income. + References No definition available. + Details
Name: | us-gaap_ComprehensiveIncomePolicyPolicyTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_EquityAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration