Significant Accounting Policies - Estimated Useful Lives of Property, Plant and Equipment (Detail)	12 Months Ended
	Dec. 31, 2019
Buildings [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives of property, plant and equipment	8 years
Buildings [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives of property, plant and equipment	30 years
Telecommunications transceivers, switching centers, transmission and other network equipment [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives of property, plant and equipment	5 years
Telecommunications transceivers, switching centers, transmission and other network equipment [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives of property, plant and equipment	10 years
Office equipment, furniture, fixtures and others [member] | Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives of property, plant and equipment	3 years
Office equipment, furniture, fixtures and others [member] | Top of range [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated useful lives of property, plant and equipment	10 years