Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net income	$ 34,355	$ 24,373
Items not requiring cash:
Depreciation	201	209
Provision for loan losses	1,072	720
Deferred tax, net	1,019	(511)
Gain on sale of securities		(24)
Gain on sale of loans	(27,813)	(17,109)
Proceeds from sales of loans	14,380,078	14,496,755
Loans and participations originated and purchased for sale	(14,394,235)	(14,813,694)
Change in mortgage servicing rights for paydowns and fair value adjustments	4,602	3,218
Net change in:
Trading securities	16,315	(112,229)
Other assets and receivables	11,504	(11,888)
Other liabilities	3,850	6,720
Other	721	55
Net cash provided by (used in) operating activities	31,669	(423,405)
Investing activities:
Net change in securities purchased under agreements to resell	(1,688)	94
Purchases of available-for-sale securities	(148,233)	(260,397)
Proceeds from sales of available-for-sale securities	0	7,371
Proceeds from calls, maturities and paydowns of available-for-sale securities	43,779	185,862
Purchases of loans	(101,227)	(51,202)
Net change in loans receivable	(166,634)	(218,434)
Purchases of premises and equipment	(754)	(1,178)
Purchases of mortgage servicing rights	(1,209)	(1,252)
Purchase of limited partnership interests	(1,845)
Cash received in acquisition of Richmac	363
Other investing activities	111	(429)
Net cash used in investing activities	(377,337)	(339,565)
Financing activities:
Net change in deposits	472,843	745,432
Proceeds from Federal Home Loan Bank advances	464,250	100,000
Repayment of Federal Home Loan Bank advances	(464,632)	(100,473)
Proceeds from issuance of preferred stock		31,581
Dividends	(5,684)	(4,336)
Net cash provided by financing activities	466,777	772,204
Net Change in Cash and Cash Equivalents	121,109	9,234
Cash and Cash Equivalents, Beginning of Period	445,701	446,801
Cash and Cash Equivalents, End of Period	566,810	456,035
Additional Cash Flows Information:
Interest paid	19,258	13,316
Income taxes paid	17,225	$ 15,349
Supplemantal Disclosure of Noncash Investing Activities:
Fair value of assets acquired	12,666
Fair value of common stock issued	8,127
Fair value of liabilities assumed	$ 4,539