Employee Benefit Plans (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amounts recognized in consolidated balance sheets
Other current liabilities	$ 1,537,000	$ 1,572,000
Pensions	65,156,000	39,194,000
Total	66,693,000	40,766,000
Amounts recognized in accumulated other comprehensive income (loss)
Net loss	49,560,000	32,279,000
Total	49,560,000	32,279,000
Pension Plan
Employee Benefits Plans
Curtailments	(1,070,000)
Expected benefit payments in next fiscal year	9,161,000
Change in benefit obligation
Benefit obligation at beginning of year	161,370,000	179,077,000
Service cost	100,000	343,000	467,000
Interest cost	7,698,000	7,237,000	7,841,000
Actuarial (gain) loss	32,018,000	(16,488,000)
Benefits paid	(9,051,000)	(8,799,000)
Curtailments	(1,070,000)
Benefit obligation at end of year	191,065,000	161,370,000	179,077,000
Change in plan assets
Fair value of plan assets at beginning of year	120,604,000	102,174,000
Actual return on plan assets	6,887,000	21,127,000
Contributions	5,932,000	6,102,000
Benefits paid	(9,051,000)	(8,799,000)
Fair value of plan assets at end of year	124,372,000	120,604,000	102,174,000
Funded status at end of year	(66,693,000)	(40,766,000)
Accumulated benefit obligation in excess of plan assets
Projected benefit obligation	191,065,000	161,370,000
Accumulated benefit obligation	191,065,000	160,340,000
Fair value of plan assets	124,372,000	120,604,000
Net Periodic Benefit Cost (Pre-tax)
Service cost	100,000	343,000	467,000
Interest cost	7,698,000	7,237,000	7,841,000
Expected return on plan assets	(8,418,000)	(7,383,000)	(6,733,000)
Amortization of prior service cost			4,000
Recognized actuarial loss	3,654,000	6,687,000	5,999,000
Net periodic benefit cost	3,034,000	6,884,000	7,578,000
Amounts Recognized in Other Comprehensive Income (Loss) (Pre-tax)
Net (gain) loss	28,802,000	(36,920,000)	9,548,000
Prior service cost			(4,000)
Total (benefit) cost recognized in other comprehensive loss	28,802,000	(36,920,000)	9,544,000
Net (benefit) cost recognized in net periodic benefit cost and other comprehensive (income) loss	31,836,000	(30,036,000)	17,122,000
Estimated net loss that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in next fiscal year	6,300,000
Weighted-average assumptions used to determine net periodic benefit cost
Discount rate (as a percent)	4.94%	4.15%	5.02%
Expected return on plan assets (as a percent)	7.00%	7.25%	7.25%
Rate of compensation increase (as a percent)		3.00%	3.00%
Weighted-average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.13%	4.94%
Rate of compensation increase (as a percent)		3.00%
Period considered for compounded returns	15 years
Qualified Pension Plan
Employee Benefits Plans
Contribution by employer in next fiscal year	4,000,000
Change in plan assets
Fair value of plan assets at beginning of year	120,604,000
Fair value of plan assets at end of year	124,372,000
Restoration Pension Plan
Employee Benefits Plans
Reduction of plan expense over the remainder of 2014	400,000
Curtailments	1,100,000
Expected benefit payments in next fiscal year	1,500,000
Change in benefit obligation
Curtailments	1,100,000
Accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	$ 28,200,000	$ 24,100,000