Fair Value - Changes in Fair Value for Items Measured at Fair Value Pursuant to Election of the Fair Value (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule of Trading Securities and Other Trading Assets [Line Items]
Interest Income	$ 153,096	$ 130,842	$ 455,374	$ 391,377
Interest (Expense)	(32,757)	(24,527)	(98,460)	(65,434)
Residential Loans Held for Sale [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other Gains and (Losses)	137	(368)	1,312	54
Interest Income	2	3	12	6
Interest (Expense)				(4)
Total Changes in Fair Values Included in Current Period Earnings	$ 139	$ (365)	$ 1,324	$ 56