CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Accumulated depreciation	$ 58,587	$ 58,117
Notes payable — credit facilities to affiliates	3,300,000	3,650,000
Accrued interest payable to affiliates	6,485	11,563
Accounts payable and accrued expenses to affiliates	$ 43,930	$ 39,772
Common stock , par value (in usd per share)	$ 0.01	$ 0.01
Common stock , shares authorized	1,100,000,000	1,100,000,000
Common stock , shares issued	348,931,490	346,763,261
Common stock , shares outstanding	348,928,336	346,760,167