Investments - Gross Unrealized Gains and (Losses) Aggregated by Investment Category Short-Term and Long-Term Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	$ 299,715	$ 326,862
Long-term investments, Estimated Fair Value	60,405	12,158
Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	3,439	52
Long-term investments, Estimated Fair Value	54
Bankers' Acceptance Drafts [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	491	242
Commercial Paper and Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	114,984
U.S. Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	162,450	313,514
Long-term investments, Estimated Fair Value	60,351	12,158
U.S. Treasury Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value		13,054
Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	18,351
Short Term [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	299,693	326,601
Investments, Gross Unrealized Gains	37	267
Investments, Gross Unrealized (Losses)	(15)	(6)
Short-term investments, Estimated Fair Value	299,715	326,862
Short Term [Member] \| Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	3,439	52
Investments, Gross Unrealized Gains
Investments, Gross Unrealized (Losses)
Short-term investments, Estimated Fair Value	3,439	52
Short Term [Member] \| Bankers' Acceptance Drafts [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	491	242
Investments, Gross Unrealized Gains
Investments, Gross Unrealized (Losses)
Short-term investments, Estimated Fair Value	491	242
Short Term [Member] \| Commercial Paper and Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	114,973
Investments, Gross Unrealized Gains	15
Investments, Gross Unrealized (Losses)	(4)
Short-term investments, Estimated Fair Value	114,984
Short Term [Member] \| Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Short-term investments, Estimated Fair Value	18,351
Short Term [Member] \| U.S. Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	162,430	313,262
Investments, Gross Unrealized Gains	22	258
Investments, Gross Unrealized (Losses)	(2)	(6)
Short-term investments, Estimated Fair Value	162,450	313,514
Short Term [Member] \| U.S. Treasury Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost		13,045
Investments, Gross Unrealized Gains		9
Short-term investments, Estimated Fair Value		13,054
Short Term [Member] \| Corporate Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	18,360
Investments, Gross Unrealized Gains
Investments, Gross Unrealized (Losses)	(9)
Long Term [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	60,428
Investments, Gross Unrealized Gains	9
Investments, Gross Unrealized (Losses)	(32)
Long-term investments, Estimated Fair Value	60,405
Long Term [Member] \| Time Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	54
Investments, Gross Unrealized Gains
Investments, Gross Unrealized (Losses)
Long-term investments, Estimated Fair Value	54
Long Term [Member] \| U.S. Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments, Cost	60,374	12,156
Investments, Gross Unrealized Gains	9	2
Investments, Gross Unrealized (Losses)	(32)
Long-term investments, Estimated Fair Value	$ 60,351	$ 12,158

- Definition

Investments in debt and equity securities which are categorized neither as held-to-maturity nor trading and which are intended to be sold or mature more than one year from the balance sheet date or operating cycle, if longer. Such securities are reported at fair value; unrealized gains (losses) related to Available-for-sale Securities are excluded from earnings and reported in a separate component of shareholders' equity (other comprehensive income), unless the Available-for-sale security is designated as a hedge or is determined to have had an other than temporary decline in fair value below its amortized cost basis. All or a portion of the unrealized holding gain (loss) of an Available-for-sale security that is designated as being hedged in a fair value hedge is recognized in earnings during the period of the hedge, as are other than temporary declines in fair value below the cost basis for investments in equity securities and debt securities that an entity intends to sell or it is more likely than not that it will be required to sell before the recovery of its amortized cost basis. Other than temporary declines in fair value below the cost basis for debt securities categorized as Available-for-sale that an entity does not intend to sell and for which it is not more likely than not that the entity will be required to sell before the recovery of its amortized cost basis are bifurcated into credit losses and losses related to all other factors. Other than temporary declines in fair value below cost basis related to credit losses are recognized in earnings, and losses related to all other factors are recognized in other comprehensive income.

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