Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 37,260	$ 28,423	$ 48,341
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	43,094	41,570	47,806
Amortization of intangibles	14,863	10,479	7,961
Amortization of deferred grants	(1,148)	(1,201)	(2,300)
Impairment losses		355	2,561
Unrealized foreign currency transaction (gains) losses, net	6,302	2,131	1,216
Stock-based compensation expense	4,873	3,467	3,582
Deferred income tax provision (benefit)	(362)	(4,867)	(3,955)
Net (gain) loss on disposal of property and equipment	201	391	(3,035)
Bad debt expense	483	1,115	532
Unrealized (gains) losses on financial instruments, net	(15)	(1,361)	4,138
(Recovery) of regulatory penalties			(407)
Amortization of deferred loan fees	259	368	585
(Gain) loss on sale of discontinued operations		10,707	(559)
Other	(56)	294	300
Changes in assets and liabilities, net of acquisition:
Receivables	(22,062)	(6,771)	8,927
Prepaid expenses	(3,931)	694	(1,042)
Other current assets	(1,177)	1,705	(3,442)
Deferred charges and other assets	(2,754)	(18,388)	1,630
Accounts payable	(1,282)	(1,589)	(6,898)
Income taxes receivable / payable	804	1,555	(4,529)
Accrued employee compensation and benefits	9,140	4,872	2,450
Other accrued expenses and current liabilities	(2,025)	11,476	(2,855)
Deferred revenue	2,826	(163)	4,243
Other long-term liabilities	925	1,252	(2,636)
Net cash provided by operating activities	86,218	86,514	102,614
Cash flows from investing activities:
Capital expenditures	(59,193)	(38,647)	(29,890)
Cash paid for business acquisition, net of cash acquired		(147,094)
Proceeds from sale of property and equipment	388	240	3,973
Investment in restricted cash	(562)	(67)	(494)
Release of restricted cash		356	396
Cash divested on sale of discontinued operations		(9,100)
Proceeds from insurance settlement		228	1,654
Net cash (used for) investing activities	(59,367)	(194,084)	(24,361)
Cash flows from financing activities:
Payments of long-term debt	(25,000)	(22,000)
Proceeds from issuance of long-term debt	32,000	113,000
Proceeds from issuance of common stock	59		311
Cash paid for repurchase of common stock	(5,479)	(7,908)	(49,993)
Proceeds from grants	201	88	(225)
Shares repurchased for minimum tax withholding on equity awards	(227)	(1,412)	(1,190)
Cash paid for loan fees related to long-term debt		(857)
Other			(8)
Net cash provided by (used for) financing activities	1,554	80,911	(51,105)
Effects of exchange rates on cash	(3,742)	2,859	(5,855)
Net increase (decrease) in cash and cash equivalents	24,663	(23,800)	21,293
Cash and cash equivalents - beginning	187,322	211,122	189,829
Cash and cash equivalents - ending	211,985	187,322	211,122
Supplemental disclosures of cash flow information:
Cash paid during period for interest	2,149	2,239	1,065
Cash paid during period for income taxes	16,889	28,822	24,631
Non-cash transactions:
Property and equipment additions in accounts payable	6,002	3,782	2,434
Unrealized gain on postretirement obligation in accumulated other comprehensive income (loss)	$ (181)	$ 36	$ 113