Employee Benefit Plans - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 entrant	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Number of new entrants since plans were frozen	0
Curtailment gain	$ 0	$ 900,000	$ 0
Multi-employer defined benefit plan, contributions	400,000	300,000	300,000
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in funded status	(1,100,000)
Funded status at end of year	(3,200,000)	(2,100,000)
Actuarial loss	5,400,000	(1,700,000)
Contributions made by the Company	3,300,000	4,500,000
Curtailment gain	0	0	0
Average future life expectancy	21 years 4 months 24 days
Estimated future employer contributions in next fiscal year	0
Other Post-retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status at end of year	(3,000,000)	(3,400,000)
Actuarial loss	(400,000)	(800,000)
Contributions made by the Company	100,000	200,000
Curtailment gain	0	900,000	0
Remaining service life	5 years 8 months 12 days
Estimated future employer contributions in next fiscal year	$ 200,000
Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Current target allocations, minimum	0.00%
Current target allocations, maximum	5.00%
Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Current target allocations, minimum	20.00%
Current target allocations, maximum	26.00%
Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Current target allocations, minimum	74.00%
Current target allocations, maximum	80.00%