Derivatives (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	$ (16,785,000)	$ (13,882,000)
Amount reclassified from accumulated other comprehensive loss	(2,453,000)	(2,249,000)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0	$ 0
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	9,600,000
Assets [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 220,000,000
Derivative @ 2.196% 28.1K [Member]
Derivative [Line Items]
Derivative, Inception Date	Oct. 16, 2013
Derivative, Maturity Date	Oct. 16, 2020
Derivative, Notional Amount	$ 28,100,000
Derivative, Description of Variable Rate Basis	1 Month LIBOR
Derivative, Fixed Interest Rate	2.196%
Derivative Liability, Fair Value, Gross Liability	$ (1,482,000)		$ (898,000)
Derivative @ 3.488% 20K [Member]
Derivative [Line Items]
Derivative, Inception Date	Jun. 15, 2017
Derivative, Maturity Date	Jun. 15, 2027
Derivative, Early Termination Date	Dec. 15, 2017
Derivative, Notional Amount	$ 20,000,000
Derivative, Description of Variable Rate Basis	3 Month LIBOR
Derivative, Fixed Interest Rate	3.4875%
Derivative Liability, Fair Value, Gross Liability	$ (3,039,000)		(1,798,000)
Derivative @ 3.48% 100K [Member]
Derivative [Line Items]
Derivative, Inception Date	Jun. 15, 2017
Derivative, Maturity Date	Jun. 15, 2027
Derivative, Early Termination Date	Dec. 15, 2017
Derivative, Notional Amount	$ 100,000,000
Derivative, Description of Variable Rate Basis	3 Month LIBOR
Derivative, Fixed Interest Rate	3.48%
Derivative Liability, Fair Value, Gross Liability	$ (15,122,000)		(8,922,000)
Swap [Member]
Derivative [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 8,300,000
Derivative @ 3.48% 100K 2 [Member]
Derivative [Line Items]
Derivative, Inception Date	Jun. 15, 2017
Derivative, Maturity Date	Jun. 15, 2027
Derivative, Early Termination Date	Dec. 15, 2017
Derivative, Notional Amount	$ 100,000,000
Derivative, Description of Variable Rate Basis	3 Month LIBOR
Derivative, Fixed Interest Rate	3.48%
Derivative Liability, Fair Value, Gross Liability	$ (15,122,000)		(8,921,000)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ (34,765,000)		$ (20,539,000)
2017 Debt issuance [Member] | Derivative [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate	3.48%