Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands | Common Stock [Member] Common Class A [Member] | Common Stock [Member] Common Class B [Member] | Common Stock [Member] | Additional Paid-in Capital [Member] | Treasury Stock, Common [Member] | Retained Earnings [Member] Common Class A [Member] | Retained Earnings [Member] Common Class B [Member] | Retained Earnings [Member] | AOCI Attributable to Parent [Member] | Parent [Member] Common Class A [Member] | Parent [Member] Common Class B [Member] | Parent [Member] | Noncontrolling Interest [Member] | Common Class A [Member] | Common Class B [Member] | Total |
Balance (in shares) at Dec. 31, 2021 | 43,108,000 | 12,399,000 | | | | | | | | | | | | | | |
Balance at Dec. 31, 2021 | | | $ 563 | $ 470,750 | $ (36,933) | | | $ 1,031,582 | $ 787 | | | $ 1,466,749 | | | | $ 1,466,749 |
Stock options exercised and stock awards (in shares) | 112,000 | | | | | | | | | | | | | | | |
Stock options exercised and stock awards | | | 1 | 2,384 | | | | | | | | 2,385 | | | | 2,385 |
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan | | | | 13,793 | | | | | | | | 13,793 | | | | 13,793 |
Vesting of restricted share awards (in shares) | | 302,000 | | | | | | | | | | | | | | |
Vesting of restricted share awards | | | 3 | (7,215) | | | | | | | | (7,212) | | | | (7,212) |
Issuance of common stock under employee stock purchase plan (in shares) | 66,000 | | | | | | | | | | | | | | | |
Issuance of common stock under employee stock purchase plan | | | 1 | 2,434 | | | | | | | | 2,435 | | | | 2,435 |
Common stock repurchases (in shares) | (192,000) | (104,000) | | | | | | | | | | | | | | |
Common stock repurchases | | | | | (15,315) | | | | | | | (15,315) | | | | (15,315) |
Cash dividends declared on Class A common stock | | | | | | $ (8,189) | $ (2,505) | | | $ (8,189) | $ (2,505) | | | $ (8,189) | $ (2,505) | |
Foreign currency translation adjustment | | | | | | | | | 445 | | | 445 | | | | 445 |
Net income | | | | | | | | 92,453 | | | | 92,453 | | | | 92,453 |
Foreign currency translation | | | | | | | | | 445 | | | 445 | | | | 445 |
Balance (in shares) at Mar. 31, 2022 | 43,094,000 | 12,597,000 | | | | | | | | | | | | | | |
Balance at Mar. 31, 2022 | | | 568 | 482,146 | (52,248) | | | 1,113,341 | 1,232 | | | 1,545,039 | | | | 1,545,039 |
Balance (in shares) at Dec. 31, 2022 | 42,345,000 | 12,083,000 | | | | | | | | | | | | | | |
Balance at Dec. 31, 2022 | | | 572 | 500,642 | (130,930) | | | 1,378,337 | (4,130) | | | 1,744,491 | | | | 1,763,022 |
Stock options exercised and stock awards (in shares) | 152 | | | | | | | | | | | | | | | |
Stock options exercised and stock awards | | | 2 | 3,412 | | | | | | | | 3,414 | | | | 3,414 |
Stock-based compensation related to stock options, restricted shares and employee stock purchase plan | | | | 13,080 | | | | | | | | 13,080 | | | | 13,080 |
Vesting of restricted share awards (in shares) | | 281,000 | | | | | | | | | | | | | | |
Vesting of restricted share awards | | | 3 | (6,964) | | | | | | | | (6,961) | | | | (6,961) |
Issuance of common stock under employee stock purchase plan (in shares) | 68,000 | | | | | | | | | | | | | | | |
Issuance of common stock under employee stock purchase plan | | | | 2,828 | | | | | | | | 2,828 | | | | 2,828 |
Common stock repurchases (in shares) | (415,000) | (56,000) | | | | | | | | | | | | | | |
Common stock repurchases | | | | | (25,280) | | | | | | | (25,280) | | | | (25,280) |
Cash dividends declared on Class A common stock | | | | | | $ (8,897) | $ (2,692) | | | $ (8,897) | $ (2,692) | | | $ (8,897) | $ (2,692) | |
Foreign currency translation adjustment | | | | | | | | | 232 | | | 232 | | | | 232 |
Net income | | | | | | | | 90,455 | | | | 90,455 | $ 335 | | | 90,790 |
Foreign currency translation | | | | | | | | | 232 | | | 232 | | | | 232 |
Balance (in shares) at Mar. 31, 2023 | 42,150,000 | 12,308,000 | | | | | | | | | | | | | | |
Balance at Mar. 31, 2023 | | | $ 577 | $ 512,998 | $ (156,210) | | | $ 1,457,203 | $ (3,898) | | | $ 1,810,670 | $ 18,866 | | | $ 1,829,536 |