Deferred Compensation Benefits Change in Benefit Obligation and Reconciliation of Fair Value (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ESBP
Changes in Benefit Obligation
Benefit obligation at beginning of period	$ 7,499	$ 8,405
Interest cost	276	243	338
Benefits paid	(737)	(720)
Actuarial loss (gain)	1,236	(429)
Effect of exchange rate changes	0	0
Benefit obligation at end of period	8,274	7,499	8,405
Reconciliation of Fair Value of Plan Assets
Fair value of plan assets at beginning of period	0	0
Actual return on plan assets	0	0
Employer contributions	737	720
Benefits paid	(737)	(720)
Fair value of plan assets at end of period	0	0	0
Accrued benefit cost	8,274	7,499
Current liabilities	714	704
Non-current liabilities	7,560	6,795
Benefit obligation	3.30%	3.87%
Net periodic pension cost	3.87%	3.02%
Salary increase rate	0.00%	0.00%
Expected return on plan assets	0.00%	0.00%
NDBP
Changes in Benefit Obligation
Benefit obligation at beginning of period	11,635	11,913
Interest cost	358	333
Benefits paid	(159)	(141)
Actuarial loss (gain)	4,896	(939)
Effect of exchange rate changes	(1,798)	469
Benefit obligation at end of period	14,932	11,635
Reconciliation of Fair Value of Plan Assets
Fair value of plan assets at beginning of period	8,752	8,143
Actual return on plan assets	359	351
Employer contributions	0	0
Benefits paid	(159)	(141)
Administrative costs		52
Effect of exchange rate changes	(1,042)	347
Fair value of plan assets at end of period	7,910	8,752
Accrued benefit cost	7,022	2,883
Current liabilities	0	0
Non-current liabilities	$ 7,022	$ 2,883
Benefit obligation	1.50%	3.20%
Net periodic pension cost	3.20%	2.80%
Salary increase rate	0.00%	0.00%
Expected return on plan assets	4.00%	4.00%