Compensatory Unit Awards and Option Plans (Tables)

12 Months Ended

Dec. 31, 2011

Compensatory Unit Awards and Option Plans [Abstract]

The weighted average fair value of options to buy Holding Units granted during 2011, 2010 and 2009 was $5.98, $6.18 and $3.52, respectively, on the date of grant, determined using the Black-Scholes option valuation model with the following assumptions:

	2011			2010			2009

Risk-free interest rate		1.9	%		2.2 – 2.3	%		1.6 – 2.1	%
Expected cash distribution yield		5.4	%		7.2 – 8.2	%		5.2 – 6.1	%
Historical volatility factor		47.3	%		46.2 – 46.6	%		40.0 – 44.6	%
Expected term	6.0 years			6.0 years			6.0 – 6.5 years

Summary of option plan activity

The following table summarizes the activity in our option plan during 2011:

	Options to Buy Holding Units			Weighted Average Exercise Price Per Option		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value

Outstanding as of December 31, 2010		10,217,871		$	41.24		6.9
Granted		70,238			21.75
Exercised		(86,543	)		17.05
Forfeited		(778,557	)		55.66
Expired		(428,780	)		50.59
Outstanding as of December 31, 2011		8,994,229			39.63		6.4	$	-
Exercisable as of December 31, 2011		3,316,961			36.65		5.6		-
Vested or expected to vest as of December 31, 2011		8,994,229			39.63		6.4		-

Summary of unvested restricted Holding Units

The following table summarizes the activity of unvested restricted Holding Units during 2011:

	Holding Units			Weighted Average Grant Date Fair Value per Holding Unit

Unvested as of December 31, 2010		21,326,859		$	24.37
Granted		1,741,930			20.52
Vested		(5,732,057	)		24.45
Forfeited		(1,762,541	)		24.68
Unvested as of December 31, 2011		15,574,191			23.88