Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions							3 Months Ended		6 Months Ended
	Jun. 03, 2016	Mar. 02, 2016	Jun. 05, 2015	Mar. 06, 2015	Jan. 13, 2015	Dec. 18, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Class Of Stock [Line Items]
Cash dividends declared per share to shareholders							$ 0.250	$ 0.225	$ 0.500	$ 0.625
Cash Distribution Approved on June 3, 2016
Class Of Stock [Line Items]
Cash distribution declaration date									Jun. 03, 2016
Cash distributions to unit holders, date of record									Jun. 30, 2016
Dividends Payable, date declared									Jun. 03, 2016
Dividends payable date of record									Jun. 30, 2016
Cash dividends declared per share to shareholders	$ 0.25
Cash distribution and dividend paid date									Jul. 21, 2016
Cash Distribution Approved on March 2, 2016
Class Of Stock [Line Items]
Cash distribution declaration date									Mar. 02, 2016
Cash distributions to unit holders, date of record									Mar. 31, 2016
Dividends Payable, date declared									Mar. 02, 2016
Dividends payable date of record									Mar. 31, 2016
Cash dividends declared per share to shareholders		$ 0.25
Cash distribution and dividend paid date									Apr. 21, 2016
Cash Distribution Approved on June 5, 2015
Class Of Stock [Line Items]
Cash distribution declaration date									Jun. 05, 2015
Cash distributions to unit holders, date of record									Jun. 30, 2015
Dividends Payable, date declared									Jun. 05, 2015
Dividends payable date of record									Jun. 30, 2015
Cash dividends declared per share to shareholders			$ 0.225
Cash distribution and dividend paid date									Jul. 23, 2015
Cash Distribution Approved on March 6, 2015
Class Of Stock [Line Items]
Cash distribution declaration date									Mar. 06, 2015
Cash distributions to unit holders, date of record									Mar. 31, 2015
Dividends Payable, date declared									Mar. 06, 2015
Dividends payable date of record									Mar. 31, 2015
Cash dividends declared per share to shareholders				$ 0.14
Cash distribution and dividend paid date									Apr. 23, 2015
Cash Distribution Approved on January 13, 2015
Class Of Stock [Line Items]
Cash distribution declaration date									Jan. 13, 2015
Cash distributions to unit holders, date of record									Jan. 20, 2015
Dividends Payable, date declared									Jan. 13, 2015
Dividends payable date of record									Jan. 20, 2015
Cash dividends declared per share to shareholders					$ 0.26
Cash distribution and dividend paid date									Jan. 29, 2015
Cash Distribution Approved on December 18, 2014
Class Of Stock [Line Items]
Cash distribution declaration date									Dec. 18, 2014
Cash distributions to unit holders, date of record									Dec. 18, 2014
Dividends Payable, date declared									Dec. 18, 2014
Dividends payable date of record									Dec. 18, 2014
Cash dividends declared per share to shareholders						$ 0.31
Cash distribution and dividend paid date									Jan. 16, 2015
Accumulated Deficit | Cash Distribution Approved on June 3, 2016
Class Of Stock [Line Items]
Cash dividends declared to shareholders	$ 10.9
Accumulated Deficit | Cash Distribution Approved on March 2, 2016
Class Of Stock [Line Items]
Cash dividends declared to shareholders		$ 10.9
Accumulated Deficit | Cash Distribution Approved on June 5, 2015
Class Of Stock [Line Items]
Cash dividends declared to shareholders			$ 9.8
Accumulated Deficit | Cash Distribution Approved on March 6, 2015
Class Of Stock [Line Items]
Cash dividends declared to shareholders				$ 6.1
Accumulated Deficit | Cash Distribution Approved on January 13, 2015
Class Of Stock [Line Items]
Cash dividends declared to shareholders					$ 9.0
Accumulated Deficit | Cash Distribution Approved on December 18, 2014
Class Of Stock [Line Items]
Cash dividends declared to shareholders						$ 10.8
InfraREIT, L.L.C. | Cash Distribution Approved on June 3, 2016
Class Of Stock [Line Items]
Cash distributions declared to unit holders, per unit	$ 0.25
Cash distribution to unit holders	$ 15.2
InfraREIT, L.L.C. | Cash Distribution Approved on March 2, 2016
Class Of Stock [Line Items]
Cash distributions declared to unit holders, per unit		$ 0.25
Cash distribution to unit holders		$ 15.2
InfraREIT, L.L.C. | Cash Distribution Approved on June 5, 2015
Class Of Stock [Line Items]
Cash distributions declared to unit holders, per unit			$ 0.225
Cash distribution to unit holders			$ 13.6
InfraREIT, L.L.C. | Cash Distribution Approved on March 6, 2015
Class Of Stock [Line Items]
Cash distributions declared to unit holders, per unit				$ 0.14
Cash distribution to unit holders				$ 8.5
InfraREIT, L.L.C. | Cash Distribution Approved on January 13, 2015
Class Of Stock [Line Items]
Cash distributions declared to unit holders, per unit					$ 0.26
Cash distribution to unit holders					$ 11.7
InfraREIT, L.L.C. | Cash Distribution Approved on December 18, 2014
Class Of Stock [Line Items]
Cash distributions declared to unit holders, per unit						$ 0.31
Cash distribution to unit holders						$ 14.1
InfraREIT, L.L.C. | Accumulated Deficit | Cash Distribution Approved on June 3, 2016
Class Of Stock [Line Items]
Cash dividends declared to shareholders	$ 10.9
InfraREIT, L.L.C. | Accumulated Deficit | Cash Distribution Approved on March 2, 2016
Class Of Stock [Line Items]
Cash dividends declared to shareholders		$ 10.9
InfraREIT, L.L.C. | Accumulated Deficit | Cash Distribution Approved on June 5, 2015
Class Of Stock [Line Items]
Cash dividends declared to shareholders			$ 9.8
InfraREIT, L.L.C. | Accumulated Deficit | Cash Distribution Approved on March 6, 2015
Class Of Stock [Line Items]
Cash dividends declared to shareholders				$ 6.1
InfraREIT, L.L.C. | Accumulated Deficit | Cash Distribution Approved on January 13, 2015
Class Of Stock [Line Items]
Cash dividends declared to shareholders					$ 9.0
InfraREIT, L.L.C. | Accumulated Deficit | Cash Distribution Approved on December 18, 2014
Class Of Stock [Line Items]
Cash dividends declared to shareholders						$ 10.8