Insurance Premiums (Undiscounted Future Amount Of Premiums Expected To Be Collected And Period Which Those Collections Are Expected To Occur) (Detail) $ in Millions	Dec. 31, 2019 USD ($)
Insurance Premiums [Abstract]
Three months ending, March 31, 2020, Expected Collection of Premiums	$ 3
Three months ending, June 30, 2020, Expected Collection of Premiums	10
Three months ending, September 30, 2020, Expected Collection of Premiums	6
Three months ending, December 31, 2020, Expected Collection of Premiums	11
Twelve months ending, December 31, 2021, Expected Collection of Premiums	28
Twelve months ending, December 31, 2022, Expected Collection of Premiums	24
Twelve months ending, December 31, 2023, Expected Collection of Premiums	23
Twelve months ending, December 31, 2024, Expected Collection of Premiums	21
Five years ending, December 31, 2029, Expected Collection of Premiums	75
Five years ending, December 31, 2034, Expected Collection of Premiums	50
Five years ending, December 31, 2039 and thereafter, Expected Collection of Premiums	63
Total, Expected Collection of Premiums	$ 314