Supplementary Financial Statement Information - Goodwill (Details 6) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Balance at beginning of year	$ 255.0	$ 253.8	$ 32.8
Acquisition	0.5	1.2	221.0
Balance at end of year	255.5	$ 255.0	$ 253.8
Precision Partners Holding Company [Domain]
Goodwill [Line Items]
Balance at end of year	222.7
AK Tube LLC [Member]
Goodwill [Line Items]
Balance at end of year	$ 32.8