CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Revenues	$ 321,976	$ 372,882	$ 989,870	$ 1,082,180
Cost of revenues	247,070	284,288	752,477	833,338
Research and development expenses	23,146	32,913	78,470	82,721
Selling, general and administrative expenses	26,154	24,368	75,904	84,869
Income from operations	25,606	31,313	83,019	81,252
Interest income and other	230	61	1,272	694
Interest expense	(1,143)	(2,517)	(3,438)	(8,564)
Income before income taxes	24,693	28,857	80,853	73,382
Income tax provision	(9,141)	(9,405)	(29,421)	(26,323)
Net income	15,552	19,452	51,432	47,059
Basic income per share: (in dollars per share)	$ 0.26	$ 0.33	$ 0.85	$ 0.79
Diluted income per share: (in dollars per share)	$ 0.26	$ 0.33	$ 0.85	$ 0.79
Net income	15,552	19,452	51,432	47,059
Other comprehensive income (loss):
Defined benefit plans, net of tax of $163, $121, $121 and $314, respectively	258	190	191	502
Unrealized gain (loss) on investments	(200)	100	400	900
Net gain (loss) on foreign exchange derivative instruments, net of tax of $(239), $(82), $59 and $(82), respectively	(383)	(131)	91	(131)
Total other comprehensive income (loss)	(325)	159	682	1,271
Comprehensive Income	$ 15,227	$ 19,611	$ 52,114	$ 48,330