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Financial Instruments - Additional Information (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Dec. 27, 2018
Financial Instruments [Line Items]            
Period cash equivalents and short-term investments have been in continuous unrealized gain (loss) position, years, maximum     1 year      
Aggregate maximum payments of repurchases of common stock     $ 5,372,000 $ 17,862,000    
Cash and cash equivalents, unrestricted $ 266,400,000   $ 266,400,000   $ 105,684,000  
Credit Agreement | Revolving Credit Facility | Wintrust Bank N A            
Financial Instruments [Line Items]            
Revolving credit facility maturity date     Sep. 08, 2024      
Revolving credit facility 125,000,000.0   $ 125,000,000.0     $ 50,000,000.0
Credit facility borrowings $ 0   $ 0   0  
Credit facility,interest rate     1.00%      
Maximum [Member] | Credit Agreement | Revolving Credit Facility | Wintrust Bank N A            
Financial Instruments [Line Items]            
Aggregate commitment amount     $ 50,000,000.0      
Aggregate maximum payments of repurchases of common stock     $ 100,000,000.0      
Percentage of aggregate amount of loan commitments     125.00%      
Minimum [Member] | Credit Agreement | Revolving Credit Facility | Wintrust Bank N A            
Financial Instruments [Line Items]            
Credit facility,interest rate     3.00%      
CCKF [Member]            
Financial Instruments [Line Items]            
Percentage of investment in equity affiliate 30.70%   30.70%      
Non controlling interest $ 3,100,000   $ 3,100,000      
CCKF [Member] | Maximum [Member]            
Financial Instruments [Line Items]            
Gain (loss) from investment in affiliate (100,000) $ 100,000 100,000 $ 200,000    
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]            
Financial Instruments [Line Items]            
Total short-term investments (available for sale), Fair value $ 190,100,000   $ 190,100,000   1,700,000  
Certificate Of Deposit Commercial Paper And Treasury Bills [Member] | Level 2 [Member]            
Financial Instruments [Line Items]            
Total short-term investments (available for sale), Fair value         $ 5,100,000