FAIR VALUE MEASUREMENTS - Summary of Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions | Mar. 31, 2021 | Dec. 31, 2020 |
Assets | | |
Available-for-sale investments | $ 921 | $ 935.9 |
Bank time deposits | | |
Assets | | |
Available-for-sale investments | 14.1 | 24.1 |
Corporate debt securities | | |
Assets | | |
Available-for-sale investments | 603.8 | 608.3 |
Asset-backed securities | | |
Assets | | |
Available-for-sale investments | 162.2 | 151.5 |
U.S. government and agency securities | | |
Assets | | |
Available-for-sale investments | 138.1 | 149.2 |
Municipal securities | | |
Assets | | |
Available-for-sale investments | 2.8 | 2.8 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | | |
Assets | | |
Cash equivalents | 25.9 | 16.2 |
Investments held for deferred compensation plans | 113.4 | 111.2 |
Derivatives | 28.8 | 8.1 |
Assets | 1,089.1 | 1,071.3 |
Liabilities | | |
Derivatives | 16.1 | 39.3 |
Deferred compensation plans | 113 | 111.6 |
Contingent consideration liabilities | 181.6 | 186.1 |
Liabilities | 310.7 | 337 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Bank time deposits | | |
Assets | | |
Available-for-sale investments | 14.1 | 24.1 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Corporate debt securities | | |
Assets | | |
Available-for-sale investments | 603.8 | 608.3 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Asset-backed securities | | |
Assets | | |
Available-for-sale investments | 162.2 | 151.5 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | U.S. government and agency securities | | |
Assets | | |
Available-for-sale investments | 138.1 | 149.1 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Municipal securities | | |
Assets | | |
Available-for-sale investments | 2.8 | 2.8 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 1 | | |
Assets | | |
Cash equivalents | 10.9 | 16.2 |
Investments held for deferred compensation plans | 113.4 | 111.2 |
Derivatives | 0 | 0 |
Assets | 180.1 | 184.3 |
Liabilities | | |
Derivatives | 0 | 0 |
Deferred compensation plans | 113 | 111.6 |
Contingent consideration liabilities | 0 | 0 |
Liabilities | 113 | 111.6 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 1 | Bank time deposits | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 1 | Corporate debt securities | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 1 | Asset-backed securities | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 1 | U.S. government and agency securities | | |
Assets | | |
Available-for-sale investments | 55.8 | 56.9 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 1 | Municipal securities | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 2 | | |
Assets | | |
Cash equivalents | 15 | 0 |
Investments held for deferred compensation plans | 0 | 0 |
Derivatives | 28.8 | 8.1 |
Assets | 909 | 887 |
Liabilities | | |
Derivatives | 16.1 | 39.3 |
Deferred compensation plans | 0 | 0 |
Contingent consideration liabilities | 0 | 0 |
Liabilities | 16.1 | 39.3 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 2 | Bank time deposits | | |
Assets | | |
Available-for-sale investments | 14.1 | 24.1 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 2 | Corporate debt securities | | |
Assets | | |
Available-for-sale investments | 603.8 | 608.3 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 2 | Asset-backed securities | | |
Assets | | |
Available-for-sale investments | 162.2 | 151.5 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 2 | U.S. government and agency securities | | |
Assets | | |
Available-for-sale investments | 82.3 | 92.2 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 2 | Municipal securities | | |
Assets | | |
Available-for-sale investments | 2.8 | 2.8 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 3 | | |
Assets | | |
Cash equivalents | 0 | 0 |
Investments held for deferred compensation plans | 0 | 0 |
Derivatives | 0 | 0 |
Assets | 0 | 0 |
Liabilities | | |
Derivatives | 0 | 0 |
Deferred compensation plans | 0 | 0 |
Contingent consideration liabilities | 181.6 | 186.1 |
Liabilities | 181.6 | 186.1 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 3 | Bank time deposits | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 3 | Corporate debt securities | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 3 | Asset-backed securities | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 3 | U.S. government and agency securities | | |
Assets | | |
Available-for-sale investments | 0 | 0 |
Estimate of Fair Value Measurement | Fair Value on a Recurring Basis | Level 3 | Municipal securities | | |
Assets | | |
Available-for-sale investments | $ 0 | $ 0 |