Employee Benefits - Postretirement Plan and Summary Information for All Defined Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Executive Retirement Plans
Summary of benefit payments under the Company's various defined benefit plans, which reflect expected future employee service, as appropriate, expected to be paid in the future periods
2016	$ 4.4
2017	14.0
2018	1.2
2019	1.2
2020	12.5
2021-2025	12.2
Amounts in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost during 2016
Actuarial loss	1.4
Total	1.4
Defined Benefit Plans
Summary of benefit payments under the Company's various defined benefit plans, which reflect expected future employee service, as appropriate, expected to be paid in the future periods
2016	3.8
2017	4.0
2018	4.2
2019	4.5
2020	4.7
2021-2025	26.7
Amounts in accumulated other comprehensive loss that are expected to be recognized as components of net periodic benefit cost during 2016
Actuarial loss	1.5
Prior service (credit) cost	0.3
Total	$ 1.8
Supplemental Bonus Plan
General disclosures of the plan
Number of shares of the entity to be contributed to the plan as a result of acquisition	258,006
Number of shares equivalent to the cash liability associated with post-employment liability	90,725
Aggregate obligation to the plan acquired	$ 5.3
(Income) expense from mark to market adjustments	$ (0.2)	$ (1.3)	$ 1.5