Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Pension and Other Postretirement Benefits - Narrative (Details) - Pension Plans - Qualified Plan - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions	$ 3.3	$ 4.9
Forecast
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions			$ 2.4