Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) - Interest Rate Swap [Member] $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016 USD ($) Caontracts	Dec. 31, 2015 USD ($) Caontracts	Aug. 31, 2016 USD ($) Caontracts
2016 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts		6	6
Derivative, Notional Amount | $		$ 115,000	$ 115,000
Derivative, Maturity Date		Dec. 31, 2016
2017 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	5	3
Derivative, Notional Amount | $	$ 65,000	$ 45,000
Derivative, Maturity Date	Dec. 31, 2017	Dec. 31, 2017
2018 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	14	11
Derivative, Notional Amount | $	$ 275,000	$ 245,000
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2018
2019 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	5	2
Derivative, Notional Amount | $	$ 60,000	$ 30,000
Derivative, Maturity Date	Dec. 31, 2019	Dec. 31, 2019
2020 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	1
Derivative, Notional Amount | $	$ 10,000
Derivative, Maturity Date	Dec. 31, 2020
2022 [Member]
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	5	1
Derivative, Notional Amount | $	$ 60,000	$ 20,000
Derivative, Maturity Date	Dec. 31, 2022	Dec. 31, 2022