Debt (Bank Of America Credit Facility) (Narrative) (Details) - USD ($) $ in Thousands					9 Months Ended	12 Months Ended
	Nov. 05, 2019	Aug. 08, 2019	Mar. 05, 2019	Mar. 03, 2016	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Contractual facility					$ 279,215	$ 252,929
Bank Of America Credit Facility [Member]
Debt Instrument [Line Items]
Contractual facility				$ 55,000	$ 55,000	$ 55,000	[1]
Reduced leverage ratio				0.25%
Earliest period subjected to repayment of borrowings					18 months
Extension period		4 months	6 months
Maturity date		Sep. 01, 2020	May 01, 2020		Oct. 01, 2020	May 01, 2020	[1]
Subsequent Event [Member] | Bank Of America Credit Facility [Member]
Debt Instrument [Line Items]
Extension period	1 month

[1] The interest rate derivatives associated with the Trust Preferred Securities and the Bank of America Credit Facility expired in October 2017 so the effective interest rate no longer applied as of December 31, 2018.