Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 41,871	$ 17,229
Accounts receivable	377,078	222,409
Prepaid expenses	24,531	10,182
Other current assets	19,924	8,111
Total current assets	463,404	257,931
Property, plant and equipment
Property, plant and equipment, gross	7,169,574	6,150,351
Less: Accumulated depreciation	(1,117,105)	(859,551)
Total property, plant and equipment, net	6,052,469	5,290,800
Investments in unconsolidated affiliates	2,229,986	1,936,603
Intangible customer relationships, net	348,683	372,391
Deferred loan costs, net	49,035	59,721
Total assets	9,143,577	7,917,446
Current liabilities
Accounts payable	32,575	37,520
Accrued gathering liabilities	54,490	108,934
Accrued interest	50,197	39,422
Accrued compensation and benefits	23,165	48,745
Due to affiliate	17,988
Accrued taxes	22,643	25,273
Other accrued liabilities	44,761	46,578
Total current liabilities	245,819	306,472
Long-term liabilities
Long-term debt	4,295,055	3,249,230
Other liabilities	90,386	8,954
Total long-term liabilities	4,385,441	3,258,184
Commitments and contingencies (Note 13)
Partners' capital
General partner interest	172,824	114,393
Total partners' capital attributable to Williams Partners L.P. (formerly Access Midstream Partners, L.P.)	4,034,627	4,098,906
Noncontrolling interest	477,690	253,884
Total partners' capital	4,512,317	4,352,790
Total liabilities and partners' capital	9,143,577	7,917,446
Gathering Systems
Property, plant and equipment
Property, plant and equipment, gross	6,700,092	5,974,940
Other Fixed Assets
Property, plant and equipment
Property, plant and equipment, gross	469,482	175,411
Common Units
Partners' capital
Limited partner units	3,501,613	3,343,145
Class B Units
Partners' capital
Limited partner units	360,190	318,472
Class C Units
Partners' capital
Limited partner units		$ 322,896