Subsequent Events (Details) $ / shares in Units, $ in Thousands		3 Months Ended			9 Months Ended
	Oct. 22, 2015 $ / shares	Mar. 31, 2016 USD ($) $ / shares shares	Sep. 30, 2015 USD ($) office	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) office	Sep. 30, 2014 USD ($)	Oct. 26, 2015 office	Dec. 31, 2014 USD ($)
Subsequent Event [Line Items]
Number of offices | office			37		37
Assets			$ 2,313,210		$ 2,313,210			$ 2,237,099
Equity			247,352		247,352			$ 228,824
NET INCOME			7,721	$ 7,708	22,352	$ 20,700
River Valley
Subsequent Event [Line Items]
Assets			513,700		513,700
Equity			$ 55,600		55,600
NET INCOME					$ 4,300
River Valley | Subsequent Event
Subsequent Event [Line Items]
Number of offices | office							14
Volume weighted average price per share, number of days	20 days
Present indicated value (USD per share) | $ / shares	$ 33.00
Scenario, Forecast | River Valley
Subsequent Event [Line Items]
Number of the Company's common stock for each share of RIVR converted | shares		0.770
Cash portion, cash per share for RIVR common stock converted (USD per share) | $ / shares		$ 9.90
Shares of common stock issued for acquisition		$ 1,940
Cash paid for acquisition		25,000
Aggregate indicated value		83,500
Cash payments for cancellation of stock options		$ 500
Common Stock | Weighted Average | Subsequent Event
Subsequent Event [Line Items]
Share price (USD per share) | $ / shares	$ 30.02