Interest Rate Swaps (Details 2) - Forward-starting Interest Rate Swap 1 [Member] $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Derivative [Line Items]
Forward-starting interest rate swap agreement, inception date	Jul. 06, 2016
Forward-starting interest rate swap agreement, effective date	Nov. 20, 2019
Forward-starting interest rate swap agreement, notional amount	$ 150.0
Forward-starting interest rate swap agreement, fixed interest rate	1.1425%
Forward-starting interest rate swap agreement, termination date	Nov. 20, 2020