Earnings Per Unit

12 Months Ended

Dec. 31, 2013

Earnings Per Unit [Abstract]

Earnings Per Unit

Note 16.  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 12) to the extent 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 (see Note 12) 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").

In a period of net losses, the Class B units, Designated Units and incremental option units are excluded from the calculation of diluted earnings per unit due to their antidilutive effect. The dilutive incremental option units are calculated using the treasury stock method, which assumes that proceeds from the exercise of all in-the-money options at the end of each period are used to repurchase common units at an average market price during the period. The amount of common units remaining after the proceeds are exhausted represents the potentially dilutive effect of the securities.

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

	For the Year Ended December 31,
	2013		2012		2011
BASIC EARNINGS PER UNIT
Numerator:
Net income attributable to limited partners	$	2,596.9	$	2,419.9	$	2,046.9
Denominator:
Weighted-average number of distribution-bearing common units outstanding		894.0		861.8		824.6
Basic earnings per unit:
Net income attributable to limited partners	$	2.90	$	2.81	$	2.48
DILUTED EARNINGS PER UNIT
Numerator:
Net income attributable to limited partners	$	2,596.9	$	2,419.9	$	2,046.9
Denominator:
Weighted-average number of units outstanding:
Distribution-bearing common units		894.0		861.8		824.6
Class B units		2.7		4.5		4.5
Designated Units		23.4		25.5		29.5
Incremental option units		1.2		1.4		1.3
Total		921.3		893.2		859.9
Diluted earnings per unit:
Net income attributable to limited partners	$	2.82	$	2.71	$	2.38