Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) (USD $)		12 Months Ended									0 Months Ended	12 Months Ended				12 Months Ended			0 Months Ended
	Dec. 31, 2012 Noncontrolling Interests [Member]	Dec. 31, 2012 Series Two Preferred Units [Member]	Dec. 31, 2012 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Nov. 15, 2012 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Aug. 15, 2012 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	May 15, 2012 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Feb. 15, 2012 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Dec. 31, 2011 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Dec. 31, 2010 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Dec. 31, 2009 Series Two Preferred Units [Member] Noncontrolling Interests [Member]	Aug. 31, 2012 series four preferred units [Member]	Dec. 31, 2012 series four preferred units [Member]	Dec. 31, 2012 series four preferred units [Member] Noncontrolling Interests [Member]	Nov. 15, 2012 series four preferred units [Member] Noncontrolling Interests [Member]	Aug. 29, 2012 series four preferred units [Member] Noncontrolling Interests [Member]	Dec. 31, 2012 OP Units [Member]	Dec. 31, 2012 Redemption Year Two Thousand Thirteen [Member]	Dec. 31, 2012 Redemption Year Two Thousand Fourteen [Member]	Oct. 04, 2012 Fountain Square [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Acquisition aggregate purchase price																			$ 385,000,000
Noncash or Part Noncash Acquisition, Debt Assumed																			211,300,000
Series Two Preferred Units (in shares)	995,997		995,997
Liquidation preference percentage			6.00%
Preferred Units liquidation preference (in dollars per share)			$ 50
Series Four Preferred Units Redeemed											366,573
Operating Units liquidation preference (in dollars per share)			$ 38.10
OP Units for each Preferred Unit (in shares)		1.312336	1.312336
Series Two Preferred Units redemption price per unit (in dollars per share)																	$ 50	$ 50.00
Dates Series Two Preferred holders can require Operating Partnership to redeem their units for cash																	May 14, 2013	May 12, 2014
Maximum redeemable Preferred Units (in shares)																	1,007,662	1,007,662
Maximum portion that may be required for redemption of total																	0.1666666667	0.1666666667
Number of holders exercising redemption rights			0					0	0	0
Units converted (in shares)		117,047														153,605
Distributions to Series Two Preferred Units (in dollars per share)				$ 0.75616	$ 0.75616	$ 0.73151	$ 0.75616							$ 0.21111
Series Four Preferred Units	1,221,527												1,221,527		1,588,100
Series Four Preferred Units Annual Dividend Payable Rate												2.00%	2.00%
Preferred Units Liquidation Preference		$ 50.00										$ 50.00	$ 50.00		$ 50.00
Payments for Repurchase of Preferred Stock and Preference Stock											18,300,000
Partners Joint Venture Ownership Percentage																			50.00%
Consideration paid																			87,000,000
Companys Joint Venture Ownership Percentage																			50.00%
Future Fixed Price to Acquire Remaining Portion of Joint venture																			$ 102,000,000
Fixed Price Option Expiration Date																			Jan. 31, 2016