Equity (Details 4) (USD $)	12 Months Ended							1 Months Ended	12 Months Ended					12 Months Ended
	Dec. 31, 2013 Item	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Restricted stock	Dec. 31, 2012 Restricted stock	Dec. 31, 2011 Restricted stock	Dec. 31, 2013 Restricted stock Automatic Awards for Eligible Directors	Jul. 31, 2011 LTIP Retention Award to Chairman and CEO	Dec. 31, 2013 LTIP Retention Award to Chairman and CEO A Units Maximum	Dec. 31, 2013 LTIP Retention Award to Chairman and CEO B Units Maximum	Dec. 31, 2013 LTIP Retention Award to Chairman and CEO C Units Maximum	Dec. 31, 2013 Employee Options	Dec. 31, 2013 1998 Stock Incentive Plan	Dec. 31, 2013 LTIP programs	Dec. 31, 2012 LTIP programs	Dec. 31, 2011 LTIP programs	Dec. 31, 2013 One-year 2010 LTIP Program	Dec. 31, 2013 Two-year 2010 LTIP Program	Dec. 31, 2013 Three-year 2010 LTIP Program	Dec. 31, 2013 2011-2013 LTIP Program	Dec. 31, 2013 2012-2014 LTIP Program	Dec. 31, 2013 2013-2015 LTIP program
Stock-based incentive plan awards
Shares reserved for issuance (in shares)													17,300,000
Vesting period				3 years			1 year					3 years		2 years
Expiration period												10 years
Value of restricted shares awarded to directors on initial election							$ 82,500
Value of restricted shares awarded to director on re-election							82,500
Value of additional restricted shares awarded to director serving as the chairperson of the Audit and Compensation Committees							10,000
Value of additional restricted shares awarded to a director serving as chairperson of a Governance and Nominating Committees							7,500
Value of additional restricted shares awarded to the Lead Director							12,500
Vesting rights percentage														50.00%
Compensation expense, net of capitalization				12,700,000	9,800,000	9,700,000								25,700,000	22,000,000	16,500,000
Percent of distributions of Operating Partnership that participants are entitled to receive during performance period														10.00%
Performance period																	1 year	2 years	3 years
Service period								8 years
Aggregate grant date fair value								120,300,000									7,200,000	14,800,000	23,000,000	35,000,000	35,000,000	33,500,000
Notes Receivable from Former CPI Stockholders	15,300,000
Award of restricted stock to employees (in shares)								1,000,000
Units earned under LTIP program (in shares)																	133,673	337,006	489,654	469,848
Units to be earned under LTIP program (in shares)									360,000	360,000	280,000
Total number of shares awarded, net of forfeiture				5,447,436
Shares of restricted stock awarded during the year, net of forfeitures				107,123	114,066	116,885
Weighted average fair value of shares granted during the year (in dollars per share)				$ 160.20	$ 146.70	$ 110.12
Amortization expense				$ 18,311,000	$ 14,001,000	$ 14,018,000
Exercised (in shares)	1,567	712	324,720									1,567
Exercised (in dollars per share)												$ 50.17
Options outstanding (in shares)												0
Exchange Rights
Limited partners units, exchange ratio	1
Common stock reserved for possible conversion (in shares)	57,274,430