Derivative Instruments - Fair Values of Derivative Instruments on the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 157,392
Liability Derivatives	2,096
Other assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	157,392	$ 57,639
Other liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	2,096	0
Interest rate swaps | Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	155,287	57,612
Interest rate swaps | Designated as Hedging Instrument | Other liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	184	0
Interest rate caps | Not Designated as Hedging Instrument | Other assets
Derivatives, Fair Value [Line Items]
Asset Derivatives	2,105	27
Interest rate caps | Not Designated as Hedging Instrument | Other liabilities
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 1,912	$ 0