Employee Benefit Plans - Schedule of Defined Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 620,623	$ 503,500
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	504,571	570,219
Service cost	85	79	104
Interest cost	25,539	23,732	25,830
Benefits paid	(24,708)	(24,806)
Actuarial (gains)/losses	115,136	(64,653)
Curtailments/Settlements	0	0
Projected benefit obligation at end of year	620,623	504,571	570,219
Plan Assets:
Fair value at beginning of year	456,591	472,417
Actual return on plan assets	63,090	8,911
Company contributions	74	69
Benefits paid	(24,708)	(24,806)
Curtailments/Settlements	0	0
Fair value at end of year	495,047	456,591	472,417
Funded status	(125,576)	(47,980)
Amounts Recognized in Consolidated Balance Sheets:
Current liabilities	0	0
Noncurrent liabilities	(125,576)	(47,980)
Total	(125,576)	(47,980)
Amounts Recognized in Accumulated Other Comprehensive Loss:
Unrecognized net actuarial loss	191,757	119,091
SERP
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	15,261	14,593
Change in Projected Benefit Obligation
Projected benefit obligation at beginning of year	14,872	15,920
Service cost	0	0
Interest cost	638	749
Benefits paid	(810)	(804)
Actuarial (gains)/losses	561	662
Curtailments/Settlements	0	(1,655)
Projected benefit obligation at end of year	15,261	14,872
Plan Assets:
Fair value at beginning of year	0	0
Actual return on plan assets	0	0
Company contributions	810	2,459
Benefits paid	(810)	(804)
Curtailments/Settlements	0	(1,655)
Fair value at end of year	0	0
Funded status	(15,261)	(14,872)
Amounts Recognized in Consolidated Balance Sheets:
Current liabilities	(1,048)	(832)
Noncurrent liabilities	(14,213)	(14,040)
Total	(15,261)	(14,872)
Amounts Recognized in Accumulated Other Comprehensive Loss:
Unrecognized net actuarial loss	$ 9,632	$ 9,343