Investments (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities, Equity Method Investments and Joint Ventures [Abstract]

Schedule of unrealized gains (losses) on available for sale securities

Unrealized investment gains (losses) on available for sale securities were as follows (in millions):

	Year Ended				Six Months Ended
	December 31, 2017		December 31, 2016		December 31, 2015
Equity securities, at cost less impairments	$	15.5	$	16.5	$	6.4
Gross unrealized gains	1.5		21.7		9.3
Gross unrealized losses	—		—		(0.8		)
Estimated fair value of equity securities	$	17.0	$	38.2	$	14.9