Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Name Accounting Standards Codification

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Changes in Carrying Amount of Goodwill by Reporting Units (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Oct. 25, 2013	Oct. 31, 2014
Goodwill [Line Items]
Goodwill	$ 770,515us-gaap_GoodwillGross	$ 757,995us-gaap_GoodwillGross	$ 781,058us-gaap_GoodwillGross
Accumulated impairment losses	(408,723)	(408,723)	(507,620)
Goodwill	361,792us-gaap_Goodwill	349,272us-gaap_Goodwill	273,438us-gaap_Goodwill
ZTEC Instruments, Inc.
Goodwill [Line Items]
Goodwill				12,520
Adjustment	27
Acquisition		12,520
Avionics Interface Technologies, LLC
Goodwill [Line Items]
Goodwill			10,516		10,516
Acquisition	10,516
Semiconductor Test
Goodwill [Line Items]
Goodwill	260,540	260,540	260,540
Accumulated impairment losses	(260,540)	(260,540)	(260,540)
System Test
Goodwill [Line Items]
Goodwill	148,183	148,183	158,699
Accumulated impairment losses	(148,183)	(148,183)	(148,183)
Goodwill			10,516
System Test \| Avionics Interface Technologies, LLC
Goodwill [Line Items]
Acquisition	10,516
Wireless Test
Goodwill [Line Items]
Goodwill	361,792	349,272	361,819
Accumulated impairment losses			(98,897)
Goodwill	361,792	349,272	262,922
Wireless Test \| ZTEC Instruments, Inc.
Goodwill [Line Items]
Adjustment	27
Acquisition		$ 12,520