SECURITIES (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Sep. 30, 2015
Available-for-sale debt securities [Abstract]
Fair value		$ 578,357	$ 576,583
Available-for-sale equity securities [Abstract]
Fair value		761,584	679,504
Available-for-sale securities [Abstract]
Amortized cost		1,335,850	1,254,661
Gross unrealized gains		16,144	10,377
Gross unrealized (losses)		(12,053)	(8,951)
Fair value		1,339,941	1,256,087
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		548,201	545,994
LESS THAN 12 MONTHS, Unrealized (Losses)		(8,073)	(5,161)
OVER 12 MONTHS, Fair Value		92,291	103,450
OVER 12 MONTHS, Unrealized (Losses)		(3,980)	(3,790)
TOTAL, Fair Value		640,492	649,444
TOTAL, Unrealized (Losses)		(12,053)	(8,951)
AMORTIZED COST [Abstract]
Due in one year or less		0	0
Due after one year through five years		3,202	1,174
Due after five years through ten years		416,377	370,087
Due after ten years		329,324	302,596
Total		748,903	673,857
Mortgage-backed securities		586,217	580,165
Common equities and mutual funds		730	639
Amortized cost		1,335,850	1,254,661
FAIR VALUE [Abstract]
Due in one year or less		0	0
Due after one year through five years		3,269	1,207
Due after five years through ten years		425,445	376,394
Due after ten years		331,842	300,989
Total		760,556	678,590
Mortgage-backed securities		578,357	576,583
Common equities and mutual funds		1,028	914
Total available for sale securities		1,339,941	1,256,087
Held-to-maturity Securities [Abstract]
Amortized cost		411,335	345,744
Gross unrealized gains		3,891	2,182
Gross unrealized (losses)		(2,144)	(1,079)
Fair value		413,082	346,847
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value		129,828	89,700
OVER 12 MONTHS, Fair Value		76,102	72,695
TOTAL, Fair Value		205,930	162,395
LESS THAN 12 MONTHS, Unrealized (Losses)		(959)	(442)
OVER 12 MONTHS, Unrealized (Losses)		(1,185)	(637)
TOTAL, Unrealized (Losses)		(2,144)	(1,079)
AMORTIZED COST [Abstract]
Due in one year or less		225	95
Due after one year through five years		9,488	8,411
Due after five years through ten years		143,173	140,145
Due after ten years		188,073	130,516
Total		340,959	279,167
Mortgage-backed securities		70,376	66,577
Amortized cost		411,335	345,744
FAIR VALUE [Abstract]
Due in one year or less		227	96
Due after one year through five years		9,475	8,430
Due after five years through ten years		145,013	140,505
Due after ten years		189,143	131,712
Total		343,858	280,743
Mortgage-backed securities		69,224	66,104
Total held to maturity securities		413,082	346,847
Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]	14,932	14,930
Unrealized gain (loss)	[1]	(2,547)	(2,263)
Fair value	[1]	12,385	12,667
AMORTIZED COST [Abstract]
Amortized cost	[1]	14,932	14,930
FAIR VALUE [Abstract]
Total available for sale securities	[1]	12,385	12,667
Moody Credit Rating, Baa3 [Member] | Key Corp Capital I [Member] | Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]		4,986
Unrealized gain (loss)	[1]		(797)
Fair value	[1]		4,189
AMORTIZED COST [Abstract]
Amortized cost	[1]		4,986
FAIR VALUE [Abstract]
Total available for sale securities	[1]		4,189
Moody Credit Rating, Baa3 [Member] | Huntington Capital Trust II SE [Member] | Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]		4,979
Unrealized gain (loss)	[1]		(903)
Fair value	[1]		4,076
AMORTIZED COST [Abstract]
Amortized cost	[1]		4,979
FAIR VALUE [Abstract]
Total available for sale securities	[1]		4,076
Moody Credit Rating, Baa2 [Member] | Key Corp Capital I [Member] | Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]	4,987
Unrealized gain (loss)	[1]	(918)
Fair value	[1]	4,069
AMORTIZED COST [Abstract]
Amortized cost	[1]	4,987
FAIR VALUE [Abstract]
Total available for sale securities	[1]	4,069
Moody Credit Rating, Baa2 [Member] | Huntington Capital Trust II SE [Member] | Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]	4,979
Unrealized gain (loss)	[1]	(1,054)
Fair value	[1]	3,925
AMORTIZED COST [Abstract]
Amortized cost	[1]	4,979
FAIR VALUE [Abstract]
Total available for sale securities	[1]	3,925
Moody Credit Rating, Baa2 [Member] | PNC Capital Trust [Member] | Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]		4,965
Unrealized gain (loss)	[1]		(563)
Fair value	[1]		4,402
AMORTIZED COST [Abstract]
Amortized cost	[1]		4,965
FAIR VALUE [Abstract]
Total available for sale securities	[1]		4,402
Moody Credit Rating, Baa1 [Member] | PNC Capital Trust [Member] | Trust Preferred Securities [Member]
Available-for-sale securities [Abstract]
Amortized cost	[1]	4,966
Unrealized gain (loss)	[1]	(575)
Fair value	[1]	4,391
AMORTIZED COST [Abstract]
Amortized cost	[1]	4,966
FAIR VALUE [Abstract]
Total available for sale securities	[1]	4,391
Debt Securities [Member]
Available-for-sale debt securities [Abstract]
Amortized cost		1,335,120	1,254,022
Gross unrealized gains		15,836	10,094
Gross unrealized (losses)		(12,043)	(8,943)
Fair value		1,338,913	1,255,173
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		548,201	545,994
LESS THAN 12 MONTHS, Unrealized (Losses)		(8,073)	(5,161)
OVER 12 MONTHS, Fair Value		92,172	103,329
OVER 12 MONTHS, Unrealized (Losses)		(3,970)	(3,782)
TOTAL, Fair Value		640,373	649,323
TOTAL, Unrealized (Losses)		(12,043)	(8,943)
Trust Preferred and Corporate Securities [Member]
Available-for-sale debt securities [Abstract]
Amortized cost		14,932	16,199
Gross unrealized gains		0	8
Gross unrealized (losses)		(2,547)	(2,263)
Fair value		12,385	13,944
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		0	0
LESS THAN 12 MONTHS, Unrealized (Losses)		0	0
OVER 12 MONTHS, Fair Value		12,385	12,667
OVER 12 MONTHS, Unrealized (Losses)		(2,547)	(2,263)
TOTAL, Fair Value		12,385	12,667
TOTAL, Unrealized (Losses)		(2,547)	(2,263)
Small Business Administration Securities [Member]
Available-for-sale debt securities [Abstract]
Amortized cost		83,704	54,493
Gross unrealized gains		1,202	1,563
Gross unrealized (losses)		(235)	0
Fair value		84,671	56,056
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		28,992
LESS THAN 12 MONTHS, Unrealized (Losses)		(235)
OVER 12 MONTHS, Fair Value		0
OVER 12 MONTHS, Unrealized (Losses)		0
TOTAL, Fair Value		28,992
TOTAL, Unrealized (Losses)		(235)
Non-bank Qualified Obligations of States and Political Subdivisions [Member]
Available-for-sale debt securities [Abstract]
Amortized cost		650,267	603,165
Gross unrealized gains		13,922	7,240
Gross unrealized (losses)		(689)	(1,815)
Fair value		663,500	608,590
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		20,924	97,006
LESS THAN 12 MONTHS, Unrealized (Losses)		(203)	(860)
OVER 12 MONTHS, Fair Value		34,033	42,583
OVER 12 MONTHS, Unrealized (Losses)		(486)	(955)
TOTAL, Fair Value		54,957	139,589
TOTAL, Unrealized (Losses)		(689)	(1,815)
Held-to-maturity Securities [Abstract]
Amortized cost		320,260	259,627
Gross unrealized gains		3,789	2,122
Gross unrealized (losses)		(890)	(419)
Fair value		323,159	261,330
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value		114,703	78,663
OVER 12 MONTHS, Fair Value		9,679	4,136
TOTAL, Fair Value		124,382	82,799
LESS THAN 12 MONTHS, Unrealized (Losses)		(811)	(365)
OVER 12 MONTHS, Unrealized (Losses)		(79)	(54)
TOTAL, Unrealized (Losses)		(890)	(419)
AMORTIZED COST [Abstract]
Amortized cost		320,260	259,627
FAIR VALUE [Abstract]
Total held to maturity securities		323,159	261,330
Mortgage-backed Securities [Member]
Available-for-sale debt securities [Abstract]
Amortized cost		586,217	580,165
Gross unrealized gains		712	1,283
Gross unrealized (losses)		(8,572)	(4,865)
Fair value		578,357	576,583
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		498,285	448,988
LESS THAN 12 MONTHS, Unrealized (Losses)		(7,635)	(4,301)
OVER 12 MONTHS, Fair Value		45,754	48,079
OVER 12 MONTHS, Unrealized (Losses)		(937)	(564)
TOTAL, Fair Value		544,039	497,067
TOTAL, Unrealized (Losses)		(8,572)	(4,865)
Held-to-maturity Securities [Abstract]
Amortized cost		70,376	66,577
Gross unrealized gains		0	0
Gross unrealized (losses)		(1,152)	(473)
Fair value		69,224	66,104
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value		11,362	5,509
OVER 12 MONTHS, Fair Value		57,863	60,595
TOTAL, Fair Value		69,225	66,104
LESS THAN 12 MONTHS, Unrealized (Losses)		(140)	(43)
OVER 12 MONTHS, Unrealized (Losses)		(1,012)	(430)
TOTAL, Unrealized (Losses)		(1,152)	(473)
AMORTIZED COST [Abstract]
Amortized cost		70,376	66,577
FAIR VALUE [Abstract]
Total held to maturity securities		69,224	66,104
Obligations of States and Political Subdivisions [Member]
Available-for-sale debt securities [Abstract]
Amortized cost		0
Gross unrealized gains		0
Gross unrealized (losses)		0
Fair value		0
Held-to-maturity Securities [Abstract]
Amortized cost		20,699	19,540
Gross unrealized gains		102	60
Gross unrealized (losses)		(102)	(187)
Fair value		20,699	19,413
Held-to-maturity Securities, Continuous Unrealized Loss Position [Abstract]
LESS THAN 12 MONTHS, Fair Value		3,763	5,528
OVER 12 MONTHS, Fair Value		8,560	7,964
TOTAL, Fair Value		12,323	13,492
LESS THAN 12 MONTHS, Unrealized (Losses)		(8)	(34)
OVER 12 MONTHS, Unrealized (Losses)		(94)	(153)
TOTAL, Unrealized (Losses)		(102)	(187)
AMORTIZED COST [Abstract]
Amortized cost		20,699	19,540
FAIR VALUE [Abstract]
Total held to maturity securities		20,699	19,413
Common Equities and Mutual Funds [Member]
Available-for-sale equity securities [Abstract]
Amortized cost		730	639
Gross unrealized gains		308	283
Gross unrealized (losses)		(10)	(8)
Fair value		1,028	914
Available-for-sale securities in a continuous unrealized loss position [Abstract]
LESS THAN 12 MONTHS, Fair Value		0	0
LESS THAN 12 MONTHS, Unrealized (Losses)		0	0
OVER 12 MONTHS, Fair Value		119	121
OVER 12 MONTHS, Unrealized (Losses)		(10)	(8)
TOTAL, Fair Value		119	121
TOTAL, Unrealized (Losses)		$ (10)	$ (8)

[1] Trust preferred securities are single-issuance. There are no known deferrals, defaults or excess subordination.