Financing Schedule of Capital Units (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Jun. 30, 2013 Second Quarter 2013 Offering [Member]		Mar. 31, 2012 February 2012 Offering [Member]
Common Unit Offering [Abstract]
Number of Common Units (in units)	12.7	[1]	9.2	[2]
Issuance Price (in dollars per unit)	$ 30.12	[1]	$ 27.55	[2]
Less Underwriting Discounts and Expenses	$ 12.3	[1]	$ 8.5	[2]
Proceeds from Issuance or Sale of Equity	$ 376.5	[1]	$ 250.2	[2]
Common Units Outstanding After Offering	220.4	[1]	184.9	[2]
Common Units Held by the Public After Offering	117.6	[1]	82.2	[2]

[1] The net proceeds of this offering were used to repay borrowings outstanding under the Partnership's credit facility.

[2] The net proceeds were used to purchase the remaining equity ownership interest in HP Storage from BPHC.