Fair Value Measurements (Details) (USD $)	3 Months Ended																																																																																																				3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member] Impaired Loans [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member] Impaired Loans [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member] Covered Real Estate Owned [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member] Covered Real Estate Owned [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member] Real Estate Held for Sale [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value Total [Member] Real Estate Held for Sale [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Impaired Loans [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Impaired Loans [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Covered Real Estate Owned [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Covered Real Estate Owned [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Real Estate Held for Sale [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member] Real Estate Held for Sale [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member] Impaired Loans [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member] Impaired Loans [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member] Covered Real Estate Owned [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member] Covered Real Estate Owned [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member] Real Estate Held for Sale [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Level 3 [Member] Real Estate Held for Sale [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Impaired Loans [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Impaired Loans [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Covered Real Estate Owned [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Covered Real Estate Owned [Member]	Jun. 30, 2014 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Real Estate Held for Sale [Member]	Jun. 30, 2013 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member] Real Estate Held for Sale [Member]	Jun. 30, 2014 Equity Securities [Member]	Sep. 30, 2013 Equity Securities [Member]	Jun. 30, 2014 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Sep. 30, 2013 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Sep. 30, 2013 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Equity Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 US Treasury and Government [Member]	Sep. 30, 2013 US Treasury and Government [Member]	Jun. 30, 2014 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Sep. 30, 2013 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Sep. 30, 2013 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 US Treasury and Government [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Obligations of States and Political Subdivisions [Member]	Sep. 30, 2013 Obligations of States and Political Subdivisions [Member]	Jun. 30, 2014 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Sep. 30, 2013 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Sep. 30, 2013 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Obligations of States and Political Subdivisions [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Corporate Debt Securities [Member]	Sep. 30, 2013 Corporate Debt Securities [Member]	Jun. 30, 2014 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Sep. 30, 2013 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Sep. 30, 2013 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Corporate Debt Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Collateralized Mortgage Backed Securities [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]	Sep. 30, 2013 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]	Jun. 30, 2014 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Sep. 30, 2013 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Sep. 30, 2013 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Sep. 30, 2013 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Sep. 30, 2013 Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Other Commercial Mortgage-Backed Securities [Member]	Sep. 30, 2013 Other Commercial Mortgage-Backed Securities [Member]	Jun. 30, 2014 Other Commercial Mortgage-Backed Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value Total [Member]	Jun. 30, 2014 Other Commercial Mortgage-Backed Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Jun. 30, 2014 Other Commercial Mortgage-Backed Securities [Member] Fair Value, Measurements, Recurring [Member] Level 3 [Member]	Jun. 30, 2014 Other Commercial Mortgage-Backed Securities [Member] Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Impaired Loans [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Impaired Loans [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Impaired Loans [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Impaired Loans [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Covered Real Estate Owned [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Covered Real Estate Owned [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Covered Real Estate Owned [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Covered Real Estate Owned [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Real Estate Held for Sale [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Real Estate Held for Sale [Member]	Jun. 30, 2014 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Real Estate Held for Sale [Member]	Jun. 30, 2013 Changes Measurement [Member] Fair Value, Measurements, Nonrecurring [Member] Real Estate Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		$ 3,103,021,000	$ 2,360,948,000	$ 3,103,021,000	$ 2,360,948,000	$ 101,981,000	$ 101,237,000	$ 0	$ 0	$ 3,001,040,000	$ 2,259,711,000																																	$ 101,981,000	$ 101,237,000	$ 101,981,000	$ 101,237,000	$ 101,981,000	$ 101,237,000	$ 0	$ 0	$ 0	$ 0	$ 721,312,000	$ 533,975,000	$ 721,312,000	$ 533,975,000	$ 0	$ 0	$ 0	$ 0	$ 721,312,000	$ 533,975,000	$ 23,277,000	$ 22,545,000	$ 23,277,000	$ 22,545,000	$ 0	$ 0	$ 0	$ 0	$ 23,277,000	$ 22,545,000	$ 485,083,000	$ 452,015,000	$ 485,083,000	$ 452,015,000	$ 0	$ 0	$ 0	$ 0	$ 485,083,000	$ 452,015,000	$ 0	$ 1,662,001,000	$ 1,251,176,000	$ 1,662,001,000	$ 1,251,176,000	$ 0	$ 0	$ 0	$ 0	$ 1,662,001,000	$ 1,251,176,000	$ 109,367,000	$ 0	$ 109,367,000	$ 0	$ 0	$ 109,367,000
Assets												62,173,000	159,892,000	10,156,000	64,500,000	8,935,000	18,312,000	43,082,000	77,080,000	0	0	0	0	0	0	0	0	62,173,000	159,892,000	10,156,000	64,500,000	8,935,000	18,312,000	43,082,000	77,080,000	0	0	0	0	0	0	0	0
Loss Related to Impaired Loans and Real Estate Held for Sale, Measured on Nonrecurring Basis																																																																																																					9,999,000	7,824,000	15,974,000	33,258,000	(775,000)	1,967,000	(1,311,000)	13,005,000	374,000	231,000	503,000	603,000	10,400,000	5,626,000	16,782,000	19,650,000
Liabilities, Fair Value Disclosure, Recurring	0
Liabilities, Fair Value Disclosure, Nonrecurring		0
Gain on sale of investments	$ 0