Employee Benefit Plans - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Cash Surrender Value of Life Insurance	$ 27,400,000		$ 27,400,000		$ 27,000,000
Deferred compensation	44,600,000		44,600,000		42,000,000
Rabbi Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets held in trust, current	43,600,000		43,600,000		42,800,000
Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets held in trust, current	16,200,000		16,200,000		$ 15,800,000
Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contributions	0	$ 0	10,000,000	$ 0
SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contributions	$ 100,000	$ 700,000	1,800,000	$ 800,000
Expected benefit payments to SERP			$ 6,900,000