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)