Pension plan and 401(k) Program - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Retirement Benefits [Abstract]
Company contributions			$ 1.2
Expected future employer contributions, next fiscal year	$ 1.7		$ 1.7
Employer's matching contribution, percent of match			50.00%
Employer's matching contribution, percent of employee's gross pay			6.00%
Employers matching contribution vesting percentage after two years of credited service			50.00%
Employers matching contribution vesting percentage after three years of credited service			100.00%
401k plan expense	$ 0.6	$ 0.6	$ 2.1	$ 2.0