CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 101,316	$ 52,293	$ 44,917
Other comprehensive income (loss):
Change in net unrealized gain (loss) on debt securities	53,739	(66,053)	(21,661)
(Gain) loss realized in net income	(729)	8,177	493
Total available for sale adjustment	53,010	(57,876)	(21,168)
Unrealized gain (loss) on currency translation	(122)	3	0
Deferred income tax effect	12,963	(15,596)	(7,414)
Total other comprehensive income (loss)	39,925	(42,277)	(13,754)
Total comprehensive income	141,241	10,016	31,163
Total comprehensive income attributable to noncontrolling interest	4,312	673	0
Total comprehensive income	$ 136,929	$ 9,343	$ 31,163