Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		3 Months Ended			9 Months Ended
	May. 11, 2015	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	May. 10, 2015	Dec. 31, 2014
Consolidated Statements of Operations and Comprehensive Income:
Gain upon acquisition of controlling interests and sale or disposal of assets and interests in unconsolidated entities, net				$ 17,717	$ 223,266	$ 154,242
Consolidated Net Income		$ 492,496		$ 296,963	$ 1,679,457	$ 1,175,534
Basic and diluted earnings per unit attributable to unitholders		$ 1.36		$ 0.81	$ 4.62	$ 3.22
Consolidated Balance Sheets:
Investment in Klepierre, at equity		$ 2,008,514			$ 2,008,514			$ 1,786,477
Total partners' equity		5,327,494			5,327,494			$ 5,951,734
Previously reported
Consolidated Statements of Operations and Comprehensive Income:
Gain upon acquisition of controlling interests and sale or disposal of assets and interests in unconsolidated entities, net					16,339
Consolidated Net Income					$ 1,472,530
Basic and diluted earnings per unit attributable to unitholders					$ 4.04
Consolidated Balance Sheets:
Investment in Klepierre, at equity		1,801,587			$ 1,801,587
Total partners' equity		5,120,567			5,120,567
Adjustment
Consolidated Statements of Operations and Comprehensive Income:
Gain upon acquisition of controlling interests and sale or disposal of assets and interests in unconsolidated entities, net					206,927
Consolidated Net Income					$ 206,927
Basic and diluted earnings per unit attributable to unitholders					$ 0.57
Consolidated Balance Sheets:
Investment in Klepierre, at equity		206,927			$ 206,927
Total partners' equity		$ 206,927			206,927
Klepierre
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Shares of common stock issued			114.0
Klepierre
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ownership interest (as a percent)	20.30%		18.30%				18.30%	28.90%
Shares sold					0
Additional shares acquired (in shares)	6.3
Corio | Klepierre
Consolidated Statements of Operations and Comprehensive Income:
Gain upon acquisition of controlling interests and sale or disposal of assets and interests in unconsolidated entities, net					$ 206,900