Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2011

Supplemental Cash Flow Information [Abstract]

Supplemental Disclosure of Cash Flow Information and Non-cash Investing and Financing Activities

The following table is a summary of the supplemental cash flow information during the years ended December 31, 2011, 2010 and 2009.

	Years Ended December 31,
	2011		2010			2009
Supplemental disclosure of cash flow information:
Interest paid	$	404,443	$	409,293		$	331,681
Income taxes paid (refund)	4,340		(5,935		)	5,597
Supplemental disclosure of non-cash investing and financing activities:
Increase (decrease) in the fair value of forward-starting interest rate swaps (note 7)	—		(114,157		)	(140,397		)
Assets acquired through capital leases and installment sales	27,094		18,682			17,351