Commitments and Contingencies (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($)
Purchase Commitment [Line Items]
Single-family properties sales in escrow | property	190	78
Single-family properties sales in escrow, selling price	$ 36.8	$ 13.6
Silver Bay Realty Trust Corp.
Gain (Loss) on Sale of Securities, Net [Abstract]
Gain (loss) on sale of equity investments			$ 3.0
Single Family Properties
Purchase Commitment [Line Items]
Purchase price of commitment to acquire single-family properties	3.3	25.3
Land
Purchase Commitment [Line Items]
Purchase price of commitment to acquire single-family properties	$ 56.2	$ 58.1
Commitment To Acquire Properties
Purchase Commitment [Line Items]
Number of properties | property	10	88