CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $)	9 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 116,803,000	$ 108,598,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,467,000	10,507,000
Cash received from FDIC under loss share	949,000	13,014,000
Stock option compensation expense	900,000	900,000
(Reversal of) provision for loan losses	(11,936,000)	3,600,000
Loss (gain) on real estate held for sale, net	598,000	(18,000)
(Increase) decrease in accrued interest receivable	(2,174,000)	872,000
Increase in FDIC loss share receivable	(2,029,000)	(1,346,000)
Increase (decrease) in income taxes payable	8,258,000	(9,446,000)
(Increase) decrease in other assets	(14,514,000)	36,665,000
Decrease in accrued expenses and other liabilities	(10,487,000)	(23,177,000)
Net cash provided by operating activities	94,835,000	140,169,000
CASH FLOWS FROM INVESTING ACTIVITIES
Net (loan originations) principal collections	(329,076,000)	475,354,000
FHLB & FRB stock redemption	9,952,000	4,391,000
Available-for-sale securities purchased	(1,080,476,000)	(506,966,000)
Principal payments and maturities of available-for-sale securities	363,103,000	198,555,000
Available-for-sale securities sold	0	43,198,000
Held-to-maturity securities purchased	0	(821,215,000)
Principal payments and maturities of held-to-maturity securities	68,981,000	428,827,000
Net cash received from acquisitions	1,776,660,000	202,308,000
Proceeds from real estate owned and held for investment	66,766,000	104,360,000
Premises and equipment purchased	(35,647,000)	(22,941,000)
Net cash provided by investing activities	840,263,000	105,871,000
CASH FLOWS FROM FINANCING ACTIVITIES
Net decrease in customer accounts	(178,161,000)	(250,364,000)
Net proceeds from borrowings	0	27,529,000
Proceeds from exercise of common stock options and related tax benefit	10,358,000	297,000
Dividends paid on common stock	(31,393,000)	(26,651,000)
Treasury stock purchased	(64,231,000)	(87,037,000)
Decrease in advance payments by borrowers for taxes and insurance	(13,930,000)	(14,387,000)
Net cash used by financing activities	(277,357,000)	(350,613,000)
Increase (decrease) in cash and cash equivalents	657,741,000	(104,573,000)
Cash and cash equivalents at beginning of period	203,563,000	751,430,000
Cash and cash equivalents at end of period	861,304,000	646,857,000
Non-cash investing activities
Non-covered real estate acquired through foreclosure	32,818,000	72,762,000
Covered real estate acquired through foreclosure	6,163,000	10,245,000
Cash paid during the period for
Interest	97,485,000	104,370,000
Income taxes	54,072,000	48,111,000
The following summarizes the non-cash activities related to acquisitions
Fair value of assets acquired	80,384,000	819,904,000
Fair value of liabilities assumed	(1,857,044,000)	(776,009,000)
Net fair value of (liabilities) assets	$ (1,776,660,000)	$ 43,895,000