Benefit Plans (Notes)	12 Months Ended
Dec. 31, 2014
Pension and Other Postretirement Benefit Expense [Abstract]
Benefit Plans	BENEFIT PLANS Certain of the benefit costs charged to us by Williams associated with employees who directly support us are described below. Additionally, allocated corporate expenses from Williams to us also include amounts related to these same employee benefits, which are not included in the amounts presented below. Pension and Other Postretirement Benefit Plans Williams has noncontributory defined benefit pension plans (Williams Pension Plan, Williams Inactive Employees Pension Plan and The Williams Companies Retirement Restoration Plan) that provide pension benefits for its eligible employees. Pension cost charged to us by Williams was $11.9 million, $22.3 million and $20.3 million for 2014, 2013, and 2012, respectively. Williams provides certain retiree health care and life insurance benefits for eligible participants that generally were employed by Williams on or before December 31, 1991 or December 31, 1995, if they were employees or retirees of Transco Energy Company and its subsidiaries. We recognized other postretirement benefit income of $13.7 million and $4.2 million for 2014 and 2013, respectively, and cost of $2.5 million for 2012. We have been allowed by rate case settlements to collect or refund in future rates any differences between the actuarially determined costs and amounts currently being recovered in rates related to other postretirement benefits. Any differences between the annual actuarially determined cost and amounts currently being recovered in rates are recorded as an adjustment to expense and collected or refunded through future rate adjustments. The amount of other postretirement benefits costs deferred as a regulatory liability at December 31, 2014 and 2013 are $39.1 million and $25.3 million, respectively. These amounts are comprised of amounts being deferred for future rate treatment of $23.0 million and $6.6 million at December 31, 2014 and 2013, respectively, and amounts of $16.1 million and $18.7 million being amortized over a period of approximately 8 years per Docket No. RP12-993 at December 31, 2014 and 2013, respectively. Effective March 1, 2013, the residual regulatory asset balance from the prior rate filing was netted against the accumulated regulatory liability. Defined Contribution Plan Williams charged us compensation expense of $6.4 million in 2014, $6.0 million in 2013 and $7.2 million in 2012 for Williams’ company matching contributions to this plan. Employee Stock-Based Compensation Plan Information The Williams Companies, Inc. 2007 Incentive Plan, as amended and restated on February 23, 2010, (Plan) was approved by stockholders on May 20, 2010. The Plan provides for Williams’ common stock based awards to both employees and non-management directors. The Plan permits the granting of various types of awards including, but not limited to, restricted stock units and stock options. Awards may be granted for no consideration other than prior and future services or based on certain financial performance targets achieved. Williams currently bills us directly for compensation expense related to stock-based compensation awards based on the fair value of the awards. We are also billed for our proportionate share of Williams’ and other affiliates’ stock-based compensation expense through various allocation processes. Total stock-based compensation expense for the years ended December 31, 2014, 2013 and 2012 was $3.0 million, $3.0 million and $2.8 million, respectively, excluding amounts allocated from WPZ and Williams.

BENEFIT PLANS

Certain of the benefit costs charged to us by Williams associated with employees who directly support us are described below. Additionally, allocated corporate expenses from Williams to us also include amounts related to these same employee benefits, which are not included in the amounts presented below.

Pension and Other Postretirement Benefit Plans

Williams has noncontributory defined benefit pension plans (Williams Pension Plan, Williams Inactive Employees Pension Plan and The Williams Companies Retirement Restoration Plan) that provide pension benefits for its eligible employees. Pension cost charged to us by Williams was $11.9 million, $22.3 million and $20.3 million for 2014, 2013, and 2012, respectively.

Williams provides certain retiree health care and life insurance benefits for eligible participants that generally were employed by Williams on or before December 31, 1991 or December 31, 1995, if they were employees or retirees of Transco Energy Company and its subsidiaries. We recognized other postretirement benefit income of $13.7 million and $4.2 million for 2014 and 2013, respectively, and cost of $2.5 million for 2012.

We have been allowed by rate case settlements to collect or refund in future rates any differences between the actuarially determined costs and amounts currently being recovered in rates related to other postretirement benefits. Any differences between the annual actuarially determined cost and amounts currently being recovered in rates are recorded as an adjustment to expense and collected or refunded through future rate adjustments. The amount of other postretirement benefits costs deferred as a regulatory liability at December 31, 2014 and 2013 are $39.1 million and $25.3 million, respectively. These amounts are comprised of amounts being deferred for future rate treatment of $23.0 million and $6.6 million at December 31, 2014 and 2013, respectively, and amounts of $16.1 million and $18.7 million being amortized over a period of approximately 8 years per Docket No. RP12-993 at December 31, 2014 and 2013, respectively. Effective March 1, 2013, the residual regulatory asset balance from the prior rate filing was netted against the accumulated regulatory liability.

Defined Contribution Plan

Williams charged us compensation expense of $6.4 million in 2014, $6.0 million in 2013 and $7.2 million in 2012 for Williams’ company matching contributions to this plan.

Employee Stock-Based Compensation Plan Information

The Williams Companies, Inc. 2007 Incentive Plan, as amended and restated on February 23, 2010, (Plan) was approved by stockholders on May 20, 2010. The Plan provides for Williams’ common stock based awards to both employees and non-management directors. The Plan permits the granting of various types of awards including, but not limited to, restricted stock units and stock options. Awards may be granted for no consideration other than prior and future services or based on certain financial performance targets achieved.

Williams currently bills us directly for compensation expense related to stock-based compensation awards based on the fair value of the awards. We are also billed for our proportionate share of Williams’ and other affiliates’ stock-based compensation expense through various allocation processes.

Total stock-based compensation expense for the years ended December 31, 2014, 2013 and 2012 was $3.0 million, $3.0 million and $2.8 million, respectively, excluding amounts allocated from WPZ and Williams.