Retirement Plans (Schedule of Benefit Obligation, Fair Value of Assets, and Funded Status of the Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	$ 17,759	$ 18,925
Service cost	36	38	$ 23
Interest cost	746	742	771
Actuarial (gain) loss	534	(1,148)
Benefits paid	(834)	(798)
Benefit obligation at end of year	18,241	17,759	18,925
Fair value of assets at beginning of year	14,235	15,205
Actual gain (loss) on plan assets	779	(172)
Employer contribution	0
Fair value of assets at end of year	14,180	14,235	15,205
Funded status at end of year	(4,061)	(3,524)
Amounts recognized in the consolidated balance sheet consist of: Other long-term liabilities	(4,061)	(3,524)
Amounts recognized in accumulated other comprehensive income consist of: Net loss	4,186	3,993
UNITED KINGDOM
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	7,862	8,797
Interest cost	259	295	360
Actuarial (gain) loss	1,532	(416)
Benefits paid	(273)	(339)
Foreign currency exchange rate changes	(1,276)	(475)
Benefit obligation at end of year	8,104	7,862	8,797
Fair value of assets at beginning of year	6,661	6,757
Actual gain (loss) on plan assets	265	307
Employer contribution	253	302
Foreign currency exchange rate changes	(1,080)	(366)
Fair value of assets at end of year	5,826	6,661	$ 6,757
Funded status at end of year	(2,278)	(1,201)
Amounts recognized in the consolidated balance sheet consist of: Other long-term liabilities	(2,278)	(1,201)
Amounts recognized in accumulated other comprehensive income consist of: Net loss	2,015	706
Amounts recognized in accumulated other comprehensive income consist of: Prior service cost	53	85
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax, Total	$ 2,068	$ 791