PRO FORMA FINANCIAL INFORMATION (Unaudited Pro Forma Basis) (Details) (Bellevue Technology Center, Powers Ferry Landing East, 1800 West Loop and West Loop I & II [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Bellevue Technology Center, Powers Ferry Landing East, 1800 West Loop and West Loop I & II [Member]
Business Acquisition [Line Items]
Revenues	$ 78,935	$ 43,766
Depreciation and amortization	32,723	15,002
Net income (loss) attributable to common stockholders	$ 14,348	$ (6,431)
Net income (loss) per common share, basic and diluted	$ 0.24	$ (0.11)
Weighted-average number of common shares outstanding, basic and diluted	59,619,000	58,836,153