Employee Benefit Plans - Textual (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) yr	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Employee Benefit Plans [Abstract]
Company Healthcare Plans, Total Costs Net of Employee Contributions	$ 109.3	$ 85.2	$ 73.4
Retirement Investment Plan, Maximum Employee Contribution	100.00%
Retirement Investment Plan, Company Match	50% of the first 6% of each participant’s elective deferrals
Retirement Investment Plan, Age Requirement	21
Retirement Investment Plan, Company Match, Vesting Percentage	100.00%
Retirement Investment Plan, Company Match, Vesting Period | yr	3
Retirement Investment Plan, Company Match, Total Costs	$ 15.0	13.9	13.2
Retirement Investment Plan, Company Match, Funded by Plan Forfeiture Account	0.9	0.5	0.5
Senior Management Bonus Program, Total Costs	$ 9.1	$ 9.0	$ 11.5