Derivatives and Hedging (Narrative) (Details) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	May. 31, 2015 USD ($)	May. 04, 2015 USD ($) derivative_contract	Jun. 30, 2015 USD ($) derivative_contract	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) derivative_contract	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) derivative_contract	Dec. 31, 2013 USD ($)
Derivatives, Fair Value [Line Items]
Realized gain on derivatives	$ 5,007		$ 5,007	$ 0	$ 5,007	$ 0
Accumulated other comprehensive loss			(5,543)	(2,912)	(5,543)	(2,912)	$ (12,436)	$ (4,202)
Gain (Loss) On Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Accumulated other comprehensive loss			$ 9,513	$ 2,161	$ 9,513	$ 2,161	$ 3,416	$ 1,233
Interest Rate Contracts [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Number of active interest rate contracts held | derivative_contract		2	4		4		1
Notional amount of interest rate fair value hedge derivatives		$ 215,000	$ 205,200		$ 205,200		$ 5,200
Derivative, lower fixed interest rate range			1.492%		1.492%
Derivative, higher fixed interest rate range			2.445%		2.445%
Derivative, maturity date					Mar. 01, 2020		Dec. 23, 2015
Derivative, fixed Interest rate							2.445%
Cash flow hedge gain (loss) to be amortized within 12 months			$ (1,600)		$ (1,600)
Interest Rate Contracts [Member] | Fair Value Hedges [Member]
Derivatives, Fair Value [Line Items]
Number of active interest rate contracts held | derivative_contract			2		2		2
Notional amount of interest rate fair value hedge derivatives			$ 64,500		$ 64,500		$ 65,300
Derivative, fixed Interest rate			7.50%		7.50%		7.50%
Derivative, lower variable interest rate range			4.26%		4.26%		4.23%
Derivative, higher variable interest rate range			4.29%		4.29%		4.26%
Interest Rate Swap [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Derivative, remaining maturity		10 years
Derivative, forward interest rate	2.00%