Borrowings (Bank Of America Line Of Credit) (Narrative) (Details) - USD ($) $ in Thousands			9 Months Ended	12 Months Ended
Aug. 07, 2020	Mar. 06, 2020	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Contractual facility			$ 269,953	$ 300,449
Bank Of America Line Of Credit [Member]
Debt Instrument [Line Items]
Maturity date		Mar. 06, 2023	Mar. 06, 2023	Mar. 06, 2023
Contractual facility		$ 5,000	$ 5,000	$ 5,000
Spread over LIBOR	1.00%

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration