Summary of Significant Accounting Policies - Activity (Details) - USD ($) $ in Thousands  | 
Mar. 31, 2021  | 
Dec. 31, 2020  | 
|---|---|---|
| Accounting Policies [Abstract] | ||
| Finance Lease, Right-of-Use Asset, after Accumulated Amortization | $ 65,216 | $ 60,121 | 
| Operating Lease, Right-of-Use Asset | $ 320,914 | $ 330,322 | 
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- References No definition available. 
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- Definition Amount, after accumulated amortization, of right-of-use asset from finance lease. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount of lessee's right to use underlying asset under operating lease. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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