Accounting Policies - Recently Issued Accounting Standards (Details) - Adjustments - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Jun. 30, 2018
Accounting Standards Update 2016-01
Recently Issued Accounting Standards
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 0.0
Accounting Standards Update 2018-02
Recently Issued Accounting Standards
Tax Cuts and Jobs Act ("TCJA") of 2017 reclassification	$ 0.0

Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration