Employee Benefit Plans - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Amortization of actuarial losses	$ 0.5	$ 0.3	$ 1.7	$ 0.8
Settlement charges	(0.8)	1.0	1.2	1.0
Assets Held In Trust Current	21.4		21.4
Life Settlement Contracts, Investment Method, Face Value	124.0		124.0
Cash Surrender Value of Life Insurance	20.1		20.1		$ 20.7
Deferred compensation	42.1		42.1		$ 42.8
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of actuarial losses	0.6	0.6	1.8	1.6
Settlement charges	1.0	1.2	1.0	1.2
Employer contributions to SERP	$ 1.7	$ 0.5	2.5	$ 3.5
Expected contributions to SERP			$ 2.2