Fair Value of Financial Instruments (Details) - Level 2 - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016
Market Approach Valuation Technique | Junior subordinated notes
Financial Instruments Not Measured at Fair Value
Market interest rate (as a percent)	6.48%	6.37%
Market Approach Valuation Technique | Mortgages | Minimum
Financial Instruments Not Measured at Fair Value
Market interest rate (as a percent)	3.81%	3.05%
Market Approach Valuation Technique | Mortgages | Maximum
Financial Instruments Not Measured at Fair Value
Market interest rate (as a percent)	5.01%	4.25%
Carrying and Fair Value | Junior subordinated notes
Financial Instruments Not Measured at Fair Value
Estimated fair value lower than carrying value	$ 16,408	$ 16,549
Carrying and Fair Value | Mortgages
Financial Instruments Not Measured at Fair Value
Estimated fair value lower than carrying value	$ 13,734	$ 10,629