Reconciliation of Benefit Obligations and Plan Assets of U.K. Plan and Japan Plan (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in plan assets:
Employer contributions	$ 2,600	$ 1,700	$ 1,300
UNITED KINGDOM
Change in benefit obligation:
Projected benefit obligation at beginning of year	35,193	34,713
Service cost	0	0
Interest cost	1,589	1,403	1,359
Actuarial (gains) losses	6,060	(889)
Benefits paid	(1,006)	(688)
Plan curtailments	0	0
Foreign currency exchange rate changes	(2,415)	654
Projected benefit obligation at end of year	39,421	35,193	34,713
Accumulated benefit obligation at end of year	39,421	35,193
Change in plan assets:
Fair value of plan assets at beginning of year	33,457	28,629
Actual return on plan assets	2,234	3,903
Employer contributions	1,000	847
Benefits paid	(1,006)	(688)
Foreign currency exchange rate changes	(2,075)	766
Fair value of plan assets at end of year	33,610	33,457	28,629
Funded status at end of year	(5,811)	(1,736)
Amounts included in accumulated other comprehensive loss not yet recognized in net periodic pension cost
Net actuarial (loss) gain	(11,890)	(7,142)
Prior service cost	0	0
Net transition obligation	0	0
Amounts expected to be amortized from accumulated other comprehensive loss into net periodic cost over the next fiscal year consists of:
Net actuarial (loss) gain	892	386
Prior service cost	0	0
Net transition obligation	0	0
JAPAN
Change in benefit obligation:
Projected benefit obligation at beginning of year	1,123	1,613
Service cost	101	99	121
Interest cost	13	10	15
Actuarial (gains) losses	(49)	(58)
Benefits paid	(340)	(928)
Plan curtailments	(252)	0
Foreign currency exchange rate changes	145	387
Projected benefit obligation at end of year	741	1,123	1,613
Accumulated benefit obligation at end of year	741	833
Change in plan assets:
Fair value of plan assets at beginning of year	537	801
Actual return on plan assets	3	4
Employer contributions	253	521
Benefits paid	(340)	(928)
Foreign currency exchange rate changes	(41)	139
Fair value of plan assets at end of year	412	537	801
Funded status at end of year	(329)	(586)
Amounts included in accumulated other comprehensive loss not yet recognized in net periodic pension cost
Net actuarial (loss) gain	0	2
Prior service cost	0	(211)
Net transition obligation	0	(163)
Amounts expected to be amortized from accumulated other comprehensive loss into net periodic cost over the next fiscal year consists of:
Net actuarial (loss) gain	0	0
Prior service cost	0	12
Net transition obligation	$ 0	$ 19