Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Revenues	$ 1,378,939		$ 1,073,222		$ 608,447
Operating expenses
Operating expenses	427,589		338,716		197,639
Depreciation and amortization expense	314,758		296,179		165,517
General and administrative expense	202,796		104,332		67,579
Other operating expense (income)	24,123		2,092		(766)
Total operating expenses	969,266		741,319		429,969
Operating income	409,673		331,903		178,478
Other income (expense)
Income from unconsolidated affiliates	205,082		130,420		67,542
Interest expense	(185,680)		(116,778)		(64,739)
Other income	872		827		320
Income before income tax expense	429,947		346,372		181,601
Income tax expense	576		5,223		3,214
Net income	429,371		341,149		178,387
Net income (loss) attributable to noncontrolling interests	31,311		5,124		(68)
Net income attributable to Williams Partners L.P. (formerly Access Midstream Partners, L.P.)	398,060		336,025		178,455
Limited partner interest in net income
Net income attributable to Williams Partners L.P. (formerly Access Midstream Partners, L.P.)	398,060		336,025		178,455
Less general partner interest in net income (Note 4)	(147,507)		(40,681)		(8,481)
Limited partner interest in net income	250,553		295,344		169,974
Common Units
Limited partner interest in net income
Limited partner interest in net income	203,543	[1]	147,706	[1]	89,019	[1]
Subordinated units
Limited partner interest in net income
Limited partner interest in net income			52,564		78,736
Limited Partner
Other income (expense)
Net income	$ 235,828		$ 206,236		$ 90,822
Limited Partner | Common Units
Limited partner interest in net income
Net income per limited partner unit - basic and diluted (Note 4)	$ 1.01	[2]	$ 0.95	[2]	$ 1.05	[2]
Limited Partner | Subordinated units
Limited partner interest in net income
Net income per limited partner unit - basic and diluted (Note 4)			$ 0.88	[2]	$ 1.07	[2]

[1] Adjusted to reflect amortization for the beneficial conversion feature

[2] The net income per limited partner unit – basic and diluted for common units and subordinated units and the weighted average limited partner units outstanding – basic and diluted for common units and subordinated units for the years ended December 31, 2014, 2013 and 2012 were adjusted to reflect the Pre-merger Unit Split.