Derivatives (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	May 31, 2014		Apr. 30, 2013
Derivative [Line Items]
Fair value of interest rate hedges recognized in other comprehensive income	$ 13,165
Interest expense	414	135
Interest rate hedges gain (loss) to be reclassified into interest expense over next 12 months	1,707
Forward Swap
Derivative [Line Items]
Aggregate Notional Amount			225,000		240,000
Fair Value When Terminated			6,312	[1]	3,156	[1]
Fair Value Deferred In Other Comprehensive Income			$ 6,312	[2]	$ 3,141	[2]

[1] Liability

[2] The amount reported in accumulated other comprehensive income will be reclassified to interest expense as interest payments are made on the related notes payable.