Note Segment reporting (Results of Operations) (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2018		Sep. 30, 2017	Sep. 30, 2018		Sep. 30, 2017
Segment Reporting Information [Line Items]
Gain from the FDIC termination agreement	$ 0	[1]	$ 0	$ 102,752	[1]	$ 0
Expenses associated with the FDIC Termination Agreement	8,100			8,100
Income tax (benefit) expense	(42,018)		$ 19,966	(35,613)		$ (48,772)
Closing Agreement With PR Department of Treasury and FDIC Termination Agreement
Segment Reporting Information [Line Items]
Income tax (benefit) expense	$ 63,900			$ 63,900

[1] Refer to Note 10 for additional information of the Termination Agreement with the FDIC.