Investments in Unconsolidated Joint Ventures: (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended			1 Months Ended		1 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended							1 Months Ended			1 Months Ended			1 Months Ended		3 Months Ended	12 Months Ended			0 Months Ended	4 Months Ended		1 Months Ended			1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended		1 Months Ended		1 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended	0 Months Ended	4 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2011 GGP Exchange store	Jun. 03, 2011 GGP Exchange	Jun. 30, 2011 GGP Exchange Mervyn's entity	Jun. 30, 2011 Superstition Springs Land	Dec. 31, 2011 Superstition Springs Land	Jun. 03, 2011 Superstition Springs Land	Feb. 28, 2011 Desert Sky Mall sqft	Dec. 31, 2011 Desert Sky Mall	Dec. 31, 2011 Eastland Mall	Dec. 31, 2011 Lake Square Mall	Dec. 31, 2011 SouthPark Mall	Dec. 31, 2011 Southridge Mall	Dec. 31, 2011 NorthPark Mall	Dec. 31, 2011 Valley Mall	Feb. 28, 2011 Kierland Commons Investment LLC	Dec. 31, 2012 Kierland Commons Investment LLC	Feb. 24, 2011 Kierland Commons Investment LLC	Feb. 28, 2011 Kierland Commons Investment LLC Kierland Commons	Feb. 24, 2011 Kierland Commons Investment LLC Kierland Commons sqft	Feb. 28, 2011 The Shops at Atlas Park sqft	Dec. 31, 2011 SDG Macerich Properties, L. P. item	Apr. 30, 2011 SDG Macerich Properties, L. P.	Dec. 31, 2011 SDG Macerich Properties, L. P.	Dec. 31, 2011 SDG Macerich Properties, L. P.	Dec. 31, 2010 SDG Macerich Properties, L. P.	Dec. 30, 2011 SDG Macerich Properties, L. P.	Oct. 26, 2012 Arrowhead Towne Center sqft	Dec. 31, 2012 Arrowhead Towne Center	Jun. 03, 2011 Arrowhead Towne Center	Jun. 30, 2011 Superstition Springs Center	Dec. 31, 2012 Superstition Springs Center	Jun. 03, 2011 Superstition Springs Center	Mar. 31, 2012 Chandler Village Center, LLC	Dec. 31, 2012 Chandler Village Center, LLC	Mar. 30, 2012 Chandler Village Center, LLC sqft	Mar. 31, 2012 Chandler Festival	Dec. 31, 2012 Chandler Festival	Mar. 30, 2012 Chandler Festival sqft	Mar. 31, 2012 SanTan Village Power Center	Mar. 30, 2012 SanTan Village Power Center sqft	May 31, 2012 Chandler Gateway sqft	Dec. 31, 2012 Chandler Gateway	Aug. 10, 2012 NorthPark Center sqft	Dec. 31, 2012 NorthPark Center	Oct. 03, 2012 FlatIron Crossing sqft	Dec. 31, 2012 FlatIron Crossing	Dec. 31, 2012 FlatIron Crossing
Investments in unconsolidated joint ventures:
Property square footage										890,000												433,000	377,000							1,196,000								273,000			500,000		491,000	260,000		1,946,000		1,443,000
Total purchase price																						$ 105,550	$ 53,750
Purchase price on acquisition										27,625																				144,400																		310,397
Purchase price																					34,162																									118,810
Purchase price funded by cash payment on acquisition					75,000					1,875																				69,025																		195,900
Purchase price paid through assumption of debt by the Company	420,123	192,566								25,750											18,613									75,375																		114,497
Percentage ownership before additional interest acquired																				24.50%
Percentage ownership by all joint venture partners before additional interest acquired																						49.00%
Ownership percentage in joint ventures																			50.00%	50.00%			50.00%						50.00%		66.70%	66.70%		66.70%	66.70%
Total ownership percentage acquired by all joint venture partners																						100.00%
Ownership percentage in property on completion of acquisition									100.00%	100.00%		100.00%	100.00%	100.00%	100.00%	100.00%	100.00%													33.30%
Other joint venture partners' ownership percentage in joint ventures																							50.00%						50.00%
Gain (loss) on sale or remeasurement of assets	29,301	389,707	576															25,019								188,264	366,312	6			115,729											23,307							84,227
Remeasurement gain on acquisition of additional interest, pro rata share																		12,510
Company's share of total purchase price																							26,875
Additional ownership interest acquired (as a percent)																														33.00%			33.30%															75.00%
Loan paid off										51,500																																45,000
Share of gain on conveyance of Granite Run Mall																									7,753
Number of anchor locations exchanged				6		5
Gain on purchase of remaining interest in property	115,729						1,734	1,734		1,868	1,868													188,264						115,729																				84,227
Number of regional shopping centers owned by investee																								11
Number of assets distributed to the Company																								6
Number of regional malls distributed by the investee to the outside partner																								5
Percentage of ownership interest sold																																				50.00%			50.00%					50.00%
Consideration received on sale of joint venture interest																																				14,795			30,975					14,315
Gain on sale of investments in unconsolidated entity																																					8,185			12,347					3,365		24,590
Cash proceeds for sale of interest in property	136,707	16,960																																		6,045			16,183					4,921
Mortgage note assumed by purchaser as sale consideration	185,000	38,968																																		8,750			14,792					9,394
Proceeds from sale of property																																										54,780
Gain on sale of property, pro rata share																																										11,504
Cash distributed to the partners																																										9,780
Gain on sale of property, pro rata share included in net income attributable to noncontrolling interests																																										$ 3,566