Net Earnings Per Common Unitholders' Interest Net Earnings (Loss) Per Common Unitholders' Interest (Earnings Distribution Allocation) (Details)	Apr. 30, 2014
Common Stock [Member] | Lower Range [Member]
Allocated Distribution	86.90%
Common Stock [Member] | Middle Range [Member]
Allocated Distribution	76.80%
Common Stock [Member] | Upper Range [Member]
Allocated Distribution	51.50%
General Partner [Member] | Lower Range [Member]
Allocated Distribution	13.10%
General Partner [Member] | Middle Range [Member]
Allocated Distribution	23.20%
General Partner [Member] | Upper Range [Member]
Allocated Distribution	48.50%