Consolidated Statements of Cash Flows (Unaudited) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
Cash flows from operating activities:
Net income	$ 41,819	$ 20,992
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	2,238	1,993
Amortization of core deposits and other intangibles	1,655	515
Capitalization of mortgage servicing rights	(29,814)	(29,659)
Net change in fair value of mortgage servicing rights	(3,528)	2,341
Stock-based compensation expense	3,819	3,154
Provision for loan losses	1,380	(1,122)
Provision for mortgage loan repurchases	392	384
Accretion of discounts on purchased loans	(3,615)	(848)
Accretion of discounts and amortization of premiums on securities, net	1,378	1,290
Loss (gain) from securities, net	89	(30)
Originations of loans held for sale	(3,287,255)	(2,944,481)
Repurchases of loans held for sale	(3,222)
Proceeds from sale of loans held for sale	3,441,316	3,071,027
Gain on sale and change in fair value of loans held for sale	(48,109)	(52,165)
Gain on sale of mortgage servicing rights		(17)
Net loss (gain) or write-downs of other real estate owned	163	(771)
Loss (gain) on other assets	87	(39)
Provision for deferred income taxes	11,081	7,952
Changes in:
Other assets and interest receivable	(8,435)	6,303
Accrued expenses and other liabilities	(42,630)	(18,785)
Net cash provided by operating activities	78,809	68,034
Activity in available-for-sale securities:
Sales	221	12,158
Maturities, prepayments and calls	34,508	41,851
Purchases	(121,108)	(22,885)
Net increase in loans	(239,188)	(114,201)
Purchases of FHLB stock	(1,229)
Proceeds from sale of mortgage servicing rights		11,952
Purchases of premises and equipment	(6,597)	(1,734)
Proceeds from the sale of premises and equipment		39
Proceeds from the sale of other real estate owned	2,209	2,930
Net cash used in investing activities	(331,184)	(69,890)
Cash flows from financing activities:
Net increase in demand and savings deposits	203,688	50,461
Net increase in time deposits	41,780	5,570
Net increase (decrease) in securities sold under agreements to repurchase	1,703	(5,218)
Decrease in short-term borrowings	(2,478)	(150,000)
Decrease in long-term debt	(3,927)	(1,102)
Share based compensation withholding obligation	(2,555)	(625)
Net proceeds from sale of common stock	669	152,721
Dividends paid	(1,839)
Net cash provided by financing activities	237,041	51,807
Net change in cash and cash equivalents	(15,334)	49,951
Cash and cash equivalents at beginning of the period	119,751	136,327
Cash and cash equivalents at end of the period	104,417	186,278
Supplemental cash flow information:
Interest paid	13,269	5,608
Taxes paid	19,112	18,122
Supplemental noncash disclosures:
Transfers from loans to other real estate owned	1,014	1,162
Transfers from other real estate owned to loans	445	36
Transfers from loans held for sale to loans	5,504	5,645
Derecognition of rebooked GNMA delinquent loans (See Note 1)	43,035
Dividends declared not paid on restricted stock units	(70)
Adoption of ASU 2016-01 (See Note 1)	$ (109)
Fair value election of mortgage servicing rights		$ 1,011