Employee Benefit Plans - Change in PBO and Assets and Reconciliations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent liabilities	$ (31,856)	$ (34,137)
Pension
Defined Benefit Plan, Change in Benefit Obligation [Rollforward]
Projected benefit obligation at beginning of year	84,005	87,355
Service cost	1,307	1,484	$ 3,923
Interest cost	3,474	3,319	10,707
Curtailment gain	(5,447)	0
Actuarial (gain) loss	1,296	(5,332)
Benefits paid	(2,883)	(2,821)
Projected benefit obligation at end of year	81,752	84,005	87,355
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	50,970	55,546
Actual return on plan assets	3,557	(1,241)
Employer contributions	29	29
Benefits paid	(2,883)	(2,821)
Other expense	(559)	(543)
Fair value of plan assets at end of year	51,114	50,970	55,546
Defined Benefit Plan, Funded Status of Plan [Abstract]
Net accrued benefit cost	(30,638)	(33,035)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current liabilities	(36)	(32)
Noncurrent liabilities	(30,602)	(33,003)
Net amount recognized	(30,638)	(33,035)
Postretirement
Defined Benefit Plan, Change in Benefit Obligation [Rollforward]
Projected benefit obligation at beginning of year	1,159	1,226
Service cost	4	11	402
Interest cost	42	52	537
Curtailment gain	0	0
Actuarial (gain) loss	99	(123)
Benefits paid	(19)	(7)
Projected benefit obligation at end of year	1,285	1,159	1,226
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	19	7
Benefits paid	(19)	(7)
Other expense	0	0
Fair value of plan assets at end of year	0	0	$ 0
Defined Benefit Plan, Funded Status of Plan [Abstract]
Net accrued benefit cost	(1,285)	(1,159)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Current liabilities	(30)	(24)
Noncurrent liabilities	(1,255)	(1,135)
Net amount recognized	(1,285)	(1,159)
Mutual Funds | Pension
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	13,774
Fair value of plan assets at end of year	13,962	13,774
Mutual Funds | Fair Value, Inputs, Level 1 [Member] | Pension
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	13,774
Fair value of plan assets at end of year	13,962	13,774
Mutual Funds | Fair Value, Inputs, Level 2 [Member] | Pension
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	0
Fair value of plan assets at end of year	$ 0	$ 0