Derivative Instruments (Effect of Derivatives on Consolidated Statements of Income) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Net effect on other comprehensive income		$ 48	$ (164)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income, net of tax (effective portion)		(2)	(164)
Interest Expense [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Realized gain on interest rate contracts	[1]	167	$ 242
Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss reclassified from accumulated other comprehensive income into interest expense (effective portion)	[1]	$ 50

[1] 1Realized gain and losses on interest rate contracts consist of net cash received or paid and interest accruals on the interest rate swaps during the periods. Net cash received or paid is included in the supplemental cash flow information within interest, net of amounts capitalized in our Condensed Consolidated Statements of Cash Flows.