Employee Benefit Plans - Narrative (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) entrant	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) entrant	Jun. 30, 2014 USD ($)	Dec. 31, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of new entrants after pension plans were frozen | entrant	0		0
Employer contributions to the pension plans	$ 0	$ 900,000	$ 0	$ 1,600,000
Assumed acceptance rate	75.00%		75.00%
Minimum | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected settlement charges					$ 2,200,000
Maximum | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected settlement charges					$ 2,500,000
Other Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net period benefit costs	$ 100,000	100,000	$ 100,000	100,000
Expected employer contributions for current year			200,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net period benefit costs	$ 100,000	$ (100,000)	100,000	$ (200,000)
Expected employer contributions for current year			$ 0