Employee Benefit Plans (Summary of Pension Plan Assets Measured at Fair Value) (Details) - USD ($) $ in Millions		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 169.8		$ 186.6
Interest of lease				26.00%
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		124.7		$ 133.0
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		41.6		49.9
Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		3.5		3.7
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		70.0		99.4
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		47.7		73.1
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		22.3		26.3
Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Mutual Funds - Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		37.4		20.9
Mutual Funds - Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		37.4		20.9
Mutual Funds - Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Mutual Funds - Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Mutual Funds - Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		39.6		39.0
Mutual Funds - Fixed Income [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		39.6		39.0
Mutual Funds - Fixed Income [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Mutual Funds - Fixed Income [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Short-term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2.8		4.3
Short-term Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Short-term Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		2.8		4.3
Short-term Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Equitable Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1.1		1.1
Equitable Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Equitable Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1.1		1.1
Equitable Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		15.4		18.2
Fixed Income [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Fixed Income [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		15.4		18.2
Fixed Income [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0.0		0.0
Coal Lease [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	3.5		3.7
Coal Lease [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0.0		0.0
Coal Lease [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	[1]	0.0		0.0
Coal Lease [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 3.5	[1]	$ 3.7	[1]	$ 4.0

[1] The Company’s interest represents approximately 26% of the lease which is currently between American Premier Underwriters (APU), the Lessor and CONSOL Energy (CONSOL), the Lessee. The lease pertains to real property mined by CONSOL located in Pennsylvania.