CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Tax on unrealized (loss) gain on available for sale securities	$ (670)	$ (3,154)	$ (4,456)	$ (5,768)
Tax on net unrealized (loss) gain on derivatives	0	(21)		(2)
Tax on adjustment for postemployment benefit obligation	$ (217)	$ (175)	$ (434)	$ (349)