Consolidated Statements of Cash Flows (Unaudited) $ in Thousands	9 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Cash flows from operating activities:
Net income	$ 63,196	$ 29,380
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	3,251	3,090
Amortization of core deposits and other intangibles	2,432	1,073
Capitalization of mortgage servicing rights	(41,555)	(45,624)
Net change in fair value of mortgage servicing rights	(1,656)	3,724
Stock-based compensation expense	5,327	4,808
Provision for loan losses	3,198	(1,906)
Provision for mortgage loan repurchases	598	794
Accretion of discounts on purchased loans	(5,745)	(3,545)
Accretion of discounts and amortization of premiums on securities, net	2,108	1,948
Loss (gain) from securities, net	116	(284)
Originations of loans held for sale	(4,777,814)	(4,612,745)
Repurchases of loans held for sale	(7,892)
Proceeds from sale of loans held for sale	5,003,669	4,711,364
Gain on sale and change in fair value of loans held for sale	(71,883)	(80,929)
Gain on sale of mortgage servicing rights		(17)
Net loss (gain) or write-downs of other real estate owned	43	(846)
(Gain) loss from other assets	(239)	350
Provision for deferred income taxes	4,416	8,226
Changes in:
Other assets and interest receivable	(28,473)	4,912
Accrued expenses and other liabilities	(12,350)	20,068
Net cash provided by operating activities	140,747	43,841
Activity in available-for-sale securities:
Sales	221	94,743
Maturities, prepayments and calls	54,576	63,167
Purchases	(137,891)	(57,441)
Net increase in loans	(352,776)	(191,033)
Purchases of FHLB stock	(2,020)
Proceeds from sale of mortgage servicing rights	39,428	11,952
Purchases of premises and equipment	(8,608)	(2,898)
Proceeds from the sale of premises and equipment	341	39
Proceeds from the sale of other real estate owned	3,666	4,082
Proceeds from the sale of other assets	869
Net cash paid in business combination		(135,141)
Net cash used in investing activities	(402,194)	(212,530)
Cash flows from financing activities:
Net increase in demand deposits	100,724	90,247
Net increase in time deposits	364,354	(22,789)
Net decrease in borrowings	(136,627)	(90,429)
Share based compensation withholding obligation	(2,637)	(858)
Net proceeds from sale of common stock	1,196	153,356
Dividends paid	(3,684)
Net cash provided by financing activities	323,326	129,527
Net change in cash and cash equivalents	61,879	(39,162)
Cash and cash equivalents at beginning of the period	119,751	136,327
Cash and cash equivalents at end of the period	181,630	97,165
Supplemental cash flow information:
Interest paid	21,690	9,652
Taxes paid	19,137	21,130
Supplemental noncash disclosures:
Transfers from loans to other real estate owned	1,490	2,958
Transfers from other real estate owned to loans	636	201
Transfers from loans held for sale to loans	13,584	9,808
Rebooked GNMA delinquent loans under optional repurchase program	43,035	13,575
Stock consideration paid in business combination		52,284
Trade date payable - securities	7,253
Dividends declared not paid on restricted stock units	134
Adoption of ASU 2016-01 (See Note 1)	$ (109)
Fair value election of mortgage servicing rights		$ 1,011