Derivatives and Hedging Activities (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) derivative	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) derivative	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) derivative
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of gain (loss) recognized in OCI on derivative	$ 2,567	$ (771)	$ 8,818	$ (136)
Amount of gain (loss) reclassified from AOCI into interest expense	$ 702	$ (16)	940	$ (238)
Interest Rate Swap | Designated as Hedging Instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount estimated to be reclassified from AOCI to interest expense over next 12 months			$ 5,500
Count | derivative	5		5		5
Notional amount	$ 570,000		$ 570,000		$ 570,000
Interest Rate Swap | Designated as Hedging Instrument | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fixed LIBOR	0.70%		0.70%		0.70%
Interest Rate Swap | Designated as Hedging Instrument | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Fixed LIBOR	2.20%		2.20%		2.20%