XML 37 R27.htm IDEA: XBRL DOCUMENT v3.7.0.1
Fair Value Measurements - Fair Values of Financial Assets Measured on Recurring Basis (Detail) - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments $ 108,325 $ 150,407
Total fair value of financial assets 193,584 244,950
Corporate bonds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 86,305 126,683
Bond and mutual funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 20,797 22,462
Equity investments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 187 225
Money market funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Assets fair value disclosure 85,259 94,543
Certificate of deposits [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 1,036 1,037
Level 1 [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total fair value of financial assets 106,243 117,230
Level 1 [Member] | Corporate bonds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 [Member] | Bond and mutual funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 20,797 22,462
Level 1 [Member] | Equity investments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 187 225
Level 1 [Member] | Money market funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Assets fair value disclosure 85,259 94,543
Level 1 [Member] | Certificate of deposits [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total fair value of financial assets 87,341 127,720
Level 2 [Member] | Corporate bonds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 86,305 126,683
Level 2 [Member] | Bond and mutual funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 [Member] | Equity investments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 [Member] | Money market funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Assets fair value disclosure 0 0
Level 2 [Member] | Certificate of deposits [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 1,036 1,037
Level 3 [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total fair value of financial assets 0 0
Level 3 [Member] | Corporate bonds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 3 [Member] | Bond and mutual funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 3 [Member] | Equity investments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments 0 0
Level 3 [Member] | Money market funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Assets fair value disclosure 0 0
Level 3 [Member] | Certificate of deposits [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Investments $ 0 $ 0