Financial Instruments and Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2012

Financial Instruments [Abstract]

Derivative activity

	2012					2011
	Interest Rate Swaps			Interest Rate Caps		Interest Rate Swaps		Interest Rate Caps
Notional amounts at January 1	$	1,496.5		$	—	$	268.1	$	—
New contracts		367.0			194.1		—		—
Acquired contracts		71.0			—		—		—
Matured or expired contracts		(393.3	)		—		—		—
Notional amounts at March 31	$	1,541.2		$	194.1	$	268.1	$	—

Fair value of financial instruments

	March 31, 2012				December 31, 2011
	Carrying Value		Fair Value		Carrying Value		Fair Value
Debt:
Credit Facilities	$	850,909	$	853,463	$	936,796	$	940,334
Senior notes		4,747,916		5,191,281		4,772,607		5,038,678
Exchangeable senior notes		1,322,800		1,456,632		1,315,448		1,431,805
Secured mortgage debt		2,806,496		2,939,167		1,725,773		1,861,261
Secured mortgage debt of consolidated investees		1,366,774		1,384,553		1,468,637		1,486,040
Other debt of consolidated investees		625,419		630,152		775,763		751,075
Other debt		660,607		660,067		387,384		389,804
Total debt	$	12,380,921	$	13,115,315	$	11,382,408	$	11,898,997