Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Interest income
Loans	$ 498,935	$ 451,290	$ 407,282
Investment securities	41,510	29,171	26,311
Federal funds sold and other	2,472	1,376	922
Total interest income	542,917	481,837	434,515
Interest expense
Deposits	106,718	60,112	35,035
FHLB advances and other borrowings	9,951	8,848	5,821
Subordinated debentures and subordinated notes payable	5,540	5,040	4,464
Total interest expense	122,209	74,000	45,320
Net interest income	420,708	407,837	389,195
Provision for loan and lease losses	40,947	17,986	21,539
Net interest income after provision for loan and lease losses	379,761	389,851	367,656
Noninterest income
Service charges and other fees	43,893	51,077	55,725
Wealth management fees	8,914	9,219	9,118
Mortgage banking income, net	4,848	5,842	7,928
Net (loss) gain on sale of securities	(178)	6	75
Net increase (decrease) in fair value of loans at fair value	61,412	(45,407)	(65,231)
Net realized and unrealized (loss) gain on derivatives	(63,444)	44,596	49,900
Other	5,287	8,276	5,699
Total noninterest income	60,732	73,609	63,214
Noninterest expense
Salaries and employee benefits	136,305	135,352	128,135
Data processing and communication	24,077	29,805	28,288
Occupancy and equipment	20,784	20,330	19,817
Professional fees	14,579	17,891	15,038
Advertising	4,493	4,507	3,983
Net loss on repossessed property and other related expenses	4,367	4,369	1,749
Acquisition expenses	0	0	710
Other	20,293	19,171	18,923
Total noninterest expense	224,898	231,425	216,643
Income before income taxes	215,595	232,035	214,227
Provision for income taxes	48,230	74,119	69,441
Net income	$ 167,365	$ 157,916	$ 144,786
Basic earnings per common share
Weighted average shares outstanding, basic (in shares)	57,154,865	58,938,169	58,770,708
Basic earnings per share (in dollars per share)	$ 2.93	$ 2.68	$ 2.46
Diluted earnings per common share
Weighted average shares outstanding, diluted (in shares)	57,257,061	59,131,650	59,029,382
Diluted earnings per share (in dollars per share)	$ 2.92	$ 2.67	$ 2.45
Dividends per share
Dividends paid	$ 62,904	$ 53,002	$ 43,474
Dividends per share (in dollars per share)	$ 1.10	$ 0.90	$ 0.74