Cash, Cash Equivalents, and Investments - Effective Maturity Dates of Available-for-Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	$ 133,620
1-2 Years	133,499
2-3 Years	96,042
3-4 Years	9,220
4-5 Years	1,892
Fair Value	374,273
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	80,386
1-2 Years	48,477
2-3 Years	54,059
3-4 Years	6,729
4-5 Years	515
Fair Value	190,166
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	26,910
1-2 Years	35,072
2-3 Years	6,194
Fair Value	68,176
Treasury Bills [Member]
Schedule of Available-for-sale Securities [Line Items]
1-2 Years	29,870
2-3 Years	22,545
Fair Value	52,415
Sovereign Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	7,383
1-2 Years	11,263
2-3 Years	10,907
4-5 Years	882
Fair Value	30,435
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	14,443
1-2 Years	8,817
2-3 Years	2,337
3-4 Years	2,491
4-5 Years	495
Fair Value	28,583
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	3,000
Fair Value	3,000
Agency Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 1 Year	1,498
Fair Value	$ 1,498