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Variable Interest Entities (Narrative) (Details) - USD ($) $ in Thousands | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Nov. 30, 2009 | Dec. 31, 2020 | Dec. 31, 2019
Variable Interest Entity [Line Items] |  |  |
Long-term debt |  | $ 100,929 | $ 100,929
Partnership total assets |  | $ 1,733,414 | 1,442,027
Liberty Mews Limited Partnership [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
Ownership in Liberty Mews Limited Partnership |  | 99.90% |
Variable Interest Entity, Not Primary Beneficiary [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
Long-term debt |  | $ 30,900 |
Equity method investments |  | 900 |
Variable Interest Entity, Not Primary Beneficiary [Member] | Liberty Mews Limited Partnership [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
Partnership total assets |  | 7,800 | $ 8,000
Subsidiaries [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
Equity method investments | $ 6,100 |  |
VIE financing | 10,600 |  |
Purchase of land for low income housing by Liberty Mews | $ 10,600 |  |
Federal investment tax credits |  | $ 8,400 |
Federal investment tax credit duration |  | 10 years |
Subsidiaries [Member] | Liberty Mews Limited Partnership [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
Ownership in Liberty Mews Limited Partnership | 99.99% |  |
Liberty Mews Limited Partnership [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
Equity method investments |  | $ 6,100 |
Impact of tax credits on total tax expense |  | $ (800) |

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