Recently Issued Accounting Pronouncements (Narrative) (Details) - USD ($)	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Prepaid expenses	$ 13,577,000				$ 10,501,000
Total shareholder's equity	363,288,000	$ 436,999,000	$ 445,188,000		465,659,000	$ 470,790,000	$ 460,870,000	$ 479,579,000	$ 475,365,000
Junior subordinated debentures	72,710,000				$ 72,081,000
Lines of credit and notes payable	0
Accounting Standards Update 2020-04 [Member] | LIBOR Indexed Junior Subordinated Debentures [Member]
Schedule of Equity Method Investments [Line Items]
Junior subordinated debentures	110,800,000
Accounting Standards Update 2020-04 [Member] | LIBOR Indexed Receivable-backed Notes Payable And Lines Of Credit [Member]
Schedule of Equity Method Investments [Line Items]
Receivable-backed notes payable and lines of credit	8,000,000
Accounting Standards Update 2020-04 [Member] | LIBOR Line Of Credit And Notes Payable [Member]
Schedule of Equity Method Investments [Line Items]
Lines of credit and notes payable	$ 162,000,000.0
Revision of Prior Period, Accounting Standards Update, Adjustment [Member] | Accounting Standards Update 2018-15 [Member]
Schedule of Equity Method Investments [Line Items]
Capitalized implementation costs				$ (1,900,000)