Fair Value Measurements, Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Mortgage servicing rights	$ 49,423		$ 72,532
Mortgage banking, net	17,029	$ 146
Equity securities	13,000		13,000
Investment securities gains (losses), net	15,091		15,090
Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Equity securities	13,444		13,444
Investment securities gains (losses), net	13,444		13,444
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
OREO(b)	6,611		3,565
Other noninterest expense	(2,273)		(1,860)
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3
Assets and Liabilities Measured at Fair Value on a Non-recurring Basis
Individually evaluated loans(a)	88,416		45,792
Provision for credit losses	(58,523)		(66,172)
Mortgage servicing rights	49,423		72,532
Mortgage banking, net	$ (17,029)		(63)
Equity securities			13,444
Investment securities gains (losses), net			$ 13,444