Derivatives And Risk Management (Interest Rate Swap Agreements) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015 Caontracts	Dec. 31, 2014 Caontracts
Derivatives, Fair Value [Line Items]
Secured Debt	$ 1,511,700	$ 1,511,700
2015 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	5	5
Derivative, Notional Amount	75,000	75,000
Derivative, Maturity Date	Dec. 31, 2015	Dec. 31, 2015
2016 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	6	5
Derivative, Notional Amount	115,000	95,000
Derivative, Maturity Date	Dec. 31, 2016	Dec. 31, 2016
2017 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	3	3
Derivative, Notional Amount	45,000	45,000
Derivative, Maturity Date	Dec. 31, 2017	Dec. 31, 2017
2018 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	11	9
Derivative, Notional Amount	245,000	205,000
Derivative, Maturity Date	Dec. 31, 2018	Dec. 31, 2018
2019 [Member] | Interest Rate Swap Agreements [Member]
Derivatives, Fair Value [Line Items]
Number of contracts	1
Derivative, Notional Amount	$ 20,000
Derivative, Maturity Date	Dec. 31, 2019