Derivative Instruments - Interest Rate Cap Contracts (Details) - Designated as Hedge - Interest rate cap agreements - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Interest rate derivatives
Notional amount	$ 540,000	$ 540,000
LIBOR
Interest rate derivatives
Interest rate cap on floating rate debt (as a percent)	3.00%

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant