Investments - Schedule of Investments (Parenthetical) (Detail) - Foxtel [Member] AUD in Millions, $ in Millions	Sep. 28, 2017 USD ($)	Sep. 28, 2017 AUD	Dec. 31, 2017 USD ($)	[1]	Dec. 31, 2017 AUD	Jun. 30, 2017 USD ($)	[1]
Schedule of Investments [Line Items]
Loan receivable from Foxtel			$ 0		AUD 481	$ 370
Equity method investment additional capital contribution	$ 388	AUD 494

[1] In May 2012, Foxtel purchased Austar United Communications Ltd. The transaction was funded by Foxtel bank debt and pro rata capital contributions made by Foxtel shareholders in the form of subordinated shareholder notes based on their respective ownership interests. The Company's share of the subordinated shareholder notes was approximately A$481 million ($370 million) as of June 30, 2017. During the three months ended September 30, 2017, Foxtel's shareholders made pro-rata capital contributions to Foxtel by way of promissory notes. The Company's share of the capital contributions was A$494 million ($388 million) at September 28, 2017, and the Company's investment in Foxtel increased by this amount. Foxtel utilized the shareholders' capital contributions to repay its subordinated shareholder notes and interest accrued in the three months ended September 30, 2017. As a result, such notes were considered to be repaid as of September 30, 2017.