Consolidated Statement of Changes in Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Limited Voting Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Noncontrolling Interests
Balance at Dec. 31, 2013	$ 1,335,521	$ 87	$ 4	$ 1,428,026	$ (2,179)	$ (409,338)	$ 318,921
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(44)					515	(559)
Other comprehensive income (loss)	(747)				(1,125)	0	378
Common dividends declared – $0.5625 per share	(59,275)					(56,350)	(2,925)
Share-based compensation	5,765	1		5,764
Issuance of 16,481 shares to directors	309			309
Issuance of 22,216,900 shares of common stock, net of offering costs	391,134	22		391,112
Issuance of 19,122 shares pursuant to TPG Management Services Agreement	375			375
Issuance of 85,649 operating partnership units	1,546						1,546
Exercise of Madison International Realty's put option related to merger with Thomas Properties Group, Inc.	(41,539)			(10,522)			(31,017)
Contribution of capital by noncontrolling interests	2,348						2,348
Distributions to noncontrolling interests	(129)						(129)
Purchase of noncontrolling interest's share of office and parking properties owned by Parkway Properties Office Fund II, L.P.	(1,963)						(1,963)
Balance at Sep. 30, 2014	$ 1,633,301	$ 110	$ 4	$ 1,815,064	$ (3,304)	$ (465,173)	$ 286,600