Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Accounts and rents receivable, allowance	$ 1,743	$ 1,266
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	40,000,000	40,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	1,460,000,000	1,460,000,000
Common stock, shares issued (in shares)	727,949,198	774,293,197
Common stock, shares outstanding (in shares)	727,949,198	774,293,197