Condensed Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Unrealized (loss) gain, net of tax benefit of $1.4 and tax provision $0.7, respectively	$ 1.4	$ (0.7)
Reclassification adjustment for realized net loss (gain) included in net income, net of tax provisions of zero for each period	0.0	0.0
Unrealized gains, net of tax provisions of $0.3 and $1.7, respectively	(0.3)	(1.7)
Reclassification adjustment for realized net (gain) loss included in net income, net of tax provisions of $0.6 and $0.3, respectively	$ 0.6	$ 0.3