Fair Value Measurements - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Bonds(2)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 31.7	$ 31.5

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

No definition available.

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant