Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Interest income
Loans	$ 451,290	$ 407,282	$ 363,728
Investment securities	29,171	26,311	24,680
Federal funds sold and other	1,376	922	574
Total interest income	481,837	434,515	388,982
Interest expense
Deposits	60,112	35,035	25,114
FHLB advances and other borrowings	8,848	5,821	4,673
Subordinated debentures and subordinated notes payable	5,040	4,464	3,737
Total interest expense	74,000	45,320	33,524
Net interest income	407,837	389,195	355,458
Provision for loan and lease losses	17,986	21,539	16,955
Net interest income after provision for loan losses	389,851	367,656	338,503
Noninterest income
Service charges and other fees	51,077	55,725	52,925
Wealth management fees	9,219	9,118	7,283
Mortgage banking income, net	5,842	7,928	7,261
Net gain on sale of securities	6	75	160
Net (decrease) increase in fair value of loans at fair value	(45,407)	(65,231)	26,314
Net realized and unrealized gain (loss) on derivatives	44,596	49,900	(48,658)
Other	8,276	5,699	3,968
Total noninterest income	73,609	63,214	49,253
Noninterest expense
Salaries and employee benefits	135,352	128,135	109,055
Data processing	29,805	28,288	25,440
Communication expenses	20,330	19,817	19,554
Advertising	17,891	15,038	13,572
Equipment expenses	4,507	3,983	4,267
Net loss recognized on repossessed property and other related expenses	4,369	1,749	1,263
Amortization of core deposits and other intangibles	1,662	2,358	3,264
Acquisition expenses	0	710	15,692
Other	17,509	16,565	15,533
Total noninterest expense	231,425	216,643	207,640
Income before income taxes	232,035	214,227	180,116
Provision for income taxes	74,119	69,441	58,863
Net income	$ 157,916	$ 144,786	$ 121,253
Basic earnings per common share
Weighted average shares outstanding, basic (in shares)	58,938,169	58,770,708	56,563,438
Basic earnings per share (in dollars per share)	$ 2.68	$ 2.46	$ 2.14
Diluted earnings per common share
Weighted average shares outstanding, diluted (in shares)	59,131,650	59,029,382	56,729,350
Diluted earnings per share (in dollars per share)	$ 2.67	$ 2.45	$ 2.14
Dividends per share
Dividends paid	$ 53,002	$ 43,474	$ 31,419
Dividends per share (in dollars per share)	$ 0.90	$ 0.74	$ 0.56