Senior Notes (Tables)

12 Months Ended

Dec. 31, 2011

Revolving Credit Facilities, Term Loan, Mortgages Payable and Scheduled Principal Repayments [Abstract]

Summary of Fixed Rate Senior Notes

	Carrying Value at December 31,						Coupon Rate at December 31, 2011	Effective  Interest Rate at December 31, 2011	Maturity Date
	2011			2010
Unsecured indebtedness:
Senior Notes	$	1,658.6		$	1,468.4		4.75% - 9.625%	5.0% - 9.9%	October 2012 - September 2020
Senior Notes — Discount		(5.4	)		(4.4	)
Senior Convertible Notes due 2011, net		—			87.5		N/A	N/A	N/A
Senior Convertible Notes due 2012, net		178.9			194.1		3.00%	5.2%	March 2012
Senior Convertible Notes due 2040, net ( A )		307.6			298.0		1.75%	5.3%	November 2040
Total Senior Notes	$	2,139.7		$	2,043.6

(A) The Company may redeem the notes any time on or after November 15, 2015, in whole or in part for cash equal to 100% of the principal amount of the notes plus accrued and unpaid interest through, but excluding, the redemption date.

Summary of Senior Convertible Notes outstanding

	Conversion Price		Option Price		Maximum Common Shares (millions)		Option Cost (millions)
Senior Convertible Notes due 2012 (A)	$	74.56	$	82.71		1.1	$	32.6
Senior Convertible Notes due 2040 (B)	$	16.19		N/A		N/A		N/A

(A) Conversion price as of December 31, 2011 and 2010.

(B) Conversion price as of December 31, 2011.

Summary of carrying amounts of debt and equity balances

	December 31,
	2011			2010
Carrying value of equity component	$	69,217		$	79,287
Principal amount of Senior Convertible Notes	$	529,509		$	637,626
Remaining unamortized debt discount		(43,004	)		(58,032	)
Net carrying value of Senior Convertible Notes	$	486,505		$	579,594