Employee Benefit Plans - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	$ 106.9	$ 115.5	$ 99.3
Level 1
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	30.9	34.2
Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	71.8	77.1
Level 3
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	4.2	4.2	$ 10.9
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	51.5	56.1
Equity securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	29.9	31.4
Equity securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	21.6	24.7
Global return fund
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	13.8	14.6
Global return fund | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	13.8	14.6
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	14.5	13.9
Corporate bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	14.5	13.9
Government bonds
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	10.6	10.6
Government bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	10.6	10.6
Real estate
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	4.2	4.2
Real estate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	0.0
Real estate | Level 3
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	4.2	4.2
LDI (Liability Driven Investment)
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	11.3	13.3
LDI (Liability Driven Investment) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	11.3	13.3
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	1.0	2.8
Cash and cash equivalents | Level 1
Defined Benefit Plan Disclosure [Line Items]
Total pension assets	$ 1.0	$ 2.8