Subsequent Events - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended			3 Months Ended	0 Months Ended
	Apr. 02, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 General Partner	Jun. 30, 2014 Cash Distributions for Limited and General Partner	Jul. 01, 2014 Subsequent Event Access Midstream Long-Term Incentive Plan	Jul. 01, 2014 Subsequent Event Management Incentive Compensation Plan	Jul. 01, 2014 Subsequent Event General Partner Williams Acquisition	Jul. 24, 2014 Subsequent Event Cash Distributions for Limited and General Partner
Subsequent Event [Line Items]
Declaration of cash distribution											$ 0.595
Cash distribution declaration date							Jul. 24, 2014				Jul. 24, 2014
Distribution payment date											Aug. 14, 2014
Distribution record date											Aug. 07, 2014
Stock-based compensation expense		$ 14.0	$ 8.9	$ 23.8	$ 16.3			$ 38.5	$ 41.1
General partnership interest	2.00%	2.00%		2.00%		1.00%				100.00%