Business combination (Fair value of major classes of identifiable assets acquired and liabilities assumed - Parenthetical) (Detail) - Reliable Financial Services $ in Thousands	Aug. 01, 2018 USD ($)
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Impaired Residential Mortgage Loans	$ 1,785,958
Fair value adjustment
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Impaired Residential Mortgage Loans	(126,908)	[1]
Auto Loan
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Impaired Residential Mortgage Loans	1,600,000
Auto Loan | Fair value adjustment
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Impaired Residential Mortgage Loans	(118,000)
Commercial Loans
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Impaired Residential Mortgage Loans	341,000
Commercial Loans | Fair value adjustment
Business Acquisition
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Impaired Residential Mortgage Loans	$ (9,000)

[1] The fair value discount is comprised of $118 million related to the retail auto loans portfolio and $9 million related to the commercial loans portfolio.