Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) - Interest Rate Swap [Member] $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017 USD ($) Caontracts	Dec. 31, 2016 USD ($) Caontracts
2017
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	6	6
Derivative, Notional Amount | $	$ 75,000	$ 75,000
Derivative, Maturity Date	Dec. 31, 2017	Dec. 31, 2017
2018
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	14	14
Derivative, Notional Amount | $	$ 275,000	$ 275,000
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2018
2019
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	6	6
Derivative, Notional Amount | $	$ 70,000	$ 70,000
Derivative, Maturity Date	Dec. 31, 2019	Dec. 31, 2019
2020
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	2	2
Derivative, Notional Amount | $	$ 20,000	$ 20,000
Derivative, Maturity Date	Dec. 31, 2020	Dec. 31, 2020
2022
Derivatives, Fair Value [Line Items]
Number of contracts | Caontracts	5	5
Derivative, Notional Amount | $	$ 60,000	$ 60,000
Derivative, Maturity Date	Dec. 31, 2022	Dec. 31, 2022