Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Accounts and rents receivable, allowance	$ 10,069	$ 10,348
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	40,000,000	40,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	1,460,000,000	1,460,000,000
Common stock, shares issued	899,870,571	889,424,572
Common stock, shares outstanding	899,870,571	889,424,572