Earnings Per Unit

3 Months Ended

Mar. 31, 2012

Earnings Per Unit [Abstract]

Earnings Per Unit

Note 13.  Earnings Per Unit

Basic earnings per unit is computed by dividing net income or loss attributable to our limited partners by the weighted-average number of our distribution-bearing units outstanding during a period, which excludes the Designated Units (see Note 10) to the extent that such units do not participate in the distributions to be paid with respect to such period.

Diluted earnings per unit is computed by dividing net income or loss attributable to our limited partners by the sum of (i) the weighted-average number of our distribution-bearing units outstanding during a period (as used in determining basic earnings per unit), (ii) the weighted-average number of our Class B units outstanding during a period, (iii) the weighted-average number of Designated Units outstanding during a period and (iv) the number of incremental common units resulting from the assumed exercise of dilutive unit options outstanding during a period (the "incremental option units").

The following table presents our calculation of basic and diluted earnings per unit for the periods presented:

	For the Three Months Ended March 31,
	2012		2011
BASIC EARNINGS PER UNIT
Numerator:
Net income attributable to limited partners	$	651.3	$	420.7
Denominator:
Common units		852.3		809.9
Time-vested restricted common units		4.3		4.0
Total		856.6		813.9
Basic earnings per unit:
Net income attributable to limited partners	$	0.76	$	0.52
DILUTED EARNINGS PER UNIT
Numerator:
Net income attributable to limited partners	$	651.3	$	420.7
Denominator:
Common units		852.3		809.9
Time-vested restricted common units		4.3		4.0
Class B units		4.5		4.5
Designated Units		26.1		30.6
Incremental option units		1.5		1.3
Total		888.7		850.3
Diluted earnings per unit:
Net income attributable to limited partners	$	0.73	$	0.49