Loans Receivable - Age Analysis of Past Due Loans (Details) (USD $)	6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Sep. 30, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Accretion of discount	$ 4,322,062	$ 5,986,428
Non-covered loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	2,861,261		2,276,068
Greater than 90 Days Past Due	1,053,332		2,493,694
Total Past Due	3,914,593		4,769,762
Current	613,138,442		541,800,958
Not covered under FDIC loss sharing agreements	617,053,035		546,570,720
Loans Greater Than 90 Days Accruing	490,395		1,739,201
Non-covered loans | 1-4 family residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,630,392		1,927,860
Greater than 90 Days Past Due	339,613		545,179
Total Past Due	1,970,005		2,473,039
Current	170,161,243		150,337,462
Not covered under FDIC loss sharing agreements	172,131,248		152,810,501
Loans Greater Than 90 Days Accruing	0		516,659
Non-covered loans | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,112,426		254,423
Greater than 90 Days Past Due	711,494		1,943,161
Total Past Due	1,823,920		2,197,584
Current	338,347,760		298,358,439
Not covered under FDIC loss sharing agreements	340,171,680		300,556,023
Loans Greater Than 90 Days Accruing	488,170		1,218,188
Non-covered loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	111,131		62,479
Greater than 90 Days Past Due	2,225		1,000
Total Past Due	113,356		63,479
Current	29,318,450		24,696,203
Not covered under FDIC loss sharing agreements	29,431,806		24,759,682
Loans Greater Than 90 Days Accruing	2,225		0
Non-covered loans | Real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0		0
Greater than 90 Days Past Due	0		0
Total Past Due	0		0
Current	70,758,469		63,485,411
Not covered under FDIC loss sharing agreements	70,758,469		63,485,411
Loans Greater Than 90 Days Accruing	0		0
Non-covered loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	7,312		31,306
Greater than 90 Days Past Due	0		4,354
Total Past Due	7,312		35,660
Current	4,552,520		4,923,443
Not covered under FDIC loss sharing agreements	4,559,832		4,959,103
Loans Greater Than 90 Days Accruing	0		4,354
Previously covered
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans Greater Than 90 Days Accruing	490,395		1,003,007
Covered loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	710,398		2,201,860
Greater than 90 Days Past Due	2,637,769		5,315,042
Total Past Due	3,348,167		7,516,902
Current	50,074,950		68,120,998
Loans receivable, net of nonaccretable differences and allowances for covered loan losses	53,423,117		75,637,900
Loans Greater Than 90 Days Accruing	2,637,769		5,315,042
Accretion of discount	4,322,062	5,986,428
Covered loans | 1-4 family residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	51,688		414,699
Greater than 90 Days Past Due	12,235		814,238
Total Past Due	63,923		1,228,937
Current	7,390,674		9,448,399
Loans receivable, net of nonaccretable differences and allowances for covered loan losses	7,454,597		10,677,336
Loans Greater Than 90 Days Accruing	12,235		814,238
Covered loans | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	601,010		1,399,520
Greater than 90 Days Past Due	2,541,537		3,949,083
Total Past Due	3,142,547		5,348,603
Current	40,969,610		55,950,984
Loans receivable, net of nonaccretable differences and allowances for covered loan losses	44,112,157		61,299,587
Loans Greater Than 90 Days Accruing	2,541,537		3,949,083
Covered loans | Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	57,700		387,641
Greater than 90 Days Past Due	83,997		551,721
Total Past Due	141,697		939,362
Current	1,672,941		2,573,517
Loans receivable, net of nonaccretable differences and allowances for covered loan losses	1,814,638		3,512,879
Loans Greater Than 90 Days Accruing	83,997		551,721
Covered loans | Real estate construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0		0
Greater than 90 Days Past Due	0		0
Total Past Due	0		0
Current	0		0
Loans receivable, net of nonaccretable differences and allowances for covered loan losses	0		0
Loans Greater Than 90 Days Accruing	0		0
Covered loans | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	0		0
Greater than 90 Days Past Due	0		0
Total Past Due	0		0
Current	41,725		148,098
Loans receivable, net of nonaccretable differences and allowances for covered loan losses	41,725		148,098
Loans Greater Than 90 Days Accruing	$ 0		$ 0