Defined Benefit Plans - Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 plan	Dec. 31, 2013	Dec. 31, 2012
Domestic
Defined Benefit Plan Disclosure [Line Items]
Reclassification adjustment from AOCI, net of income taxes	$ 200,000	$ 300,000	$ 200,000
Estimated unrecognized loss that will be amortized from AOCI, net of income taxes	200,000
Number of plans	2
Benefit obligation	6,700,000	6,600,000
Fair value of plan assets	5,100,000	4,900,000
Annual rate of return on plan assets	7.00%	7.00%
Estimated future benefit payments	400,000
Maximum | Domestic
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.50%	4.50%
Minimum | Domestic
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.30%	4.30%
United Kingdom Subsidiary | UK Plan
Defined Benefit Plan Disclosure [Line Items]
Underfunded status of UK Plan	50,711,000	39,066,000
Annual rate of inflation	2.00%	2.30%
Average life expectancy	28 years
Reclassification adjustment from AOCI, net of income taxes	1,600,000	2,000,000	1,900,000
Estimated unrecognized loss that will be amortized from AOCI, net of income taxes	2,100,000
Future estimated employer contributions to be paid next year	5,700,000
Benefit obligation	332,806,000	308,877,000	302,306,000
Fair value of plan assets	$ 282,095,000	$ 269,811,000	$ 239,650,000
Discount rate	3.60%	4.60%
Annual rate of return on plan assets	6.70%	6.70%	6.70%