Stock Compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock compensation
Stock compensation expense	$ 177.9	$ 166.6	$ 148.2
Stock Compensation Expense Capitalized	$ 0.6	0.4	0.1
Weighted-average fair value assumptions
Valuation method	Black-Scholes valuation model
Dividend yield (as a percent)	0.00%
Research and Development Expense
Stock compensation
Stock compensation expense	$ 120.4	114.0	101.1
Selling, General and Administrative Expenses
Stock compensation
Stock compensation expense	56.6	51.9	47.1
Cost of product revenues
Stock compensation
Stock compensation expense	1.0	0.7
Employee Stock
Stock compensation
Stock compensation expense	$ 4.6	$ 3.4	$ 3.7
Weighted-average fair value assumptions
Average risk-free interest rates (as a percent)	0.17%	1.82%	2.62%
Average expected life (in years)	6 months	6 months	6 months
Volatility (as a percent)	45.00%	31.00%	46.00%
Weighted-average fair value (in dollars per share)	$ 19.13	$ 14.04	$ 15.80
Stock Options
Stock compensation
Assumed annualized forfeiture rate (as a percent)	5.00%
Weighted-average fair value assumptions
Average risk-free interest rates (as a percent)	0.80%	2.27%	2.61%
Average expected life (in years)	4 years 11 months 23 days	5 years 3 months 7 days	5 years 3 months 3 days
Volatility (as a percent)	40.00%	45.00%	45.00%
Weighted-average fair value (in dollars per share)	$ 32.65	$ 32.38	$ 34.20
Unrecognized compensation
Unrecognized compensation cost for nonvested option (in dollars)	$ 75.0
Vesting period of recognition of the unrecognized compensation cost of nonvested awards	1 year 2 months 12 days
Restricted Stock Units (RSUs)
Stock compensation
Assumed annualized forfeiture rate (as a percent)	5.00%
Unrecognized compensation
Unrecognized compensation cost for nonvested option (in dollars)	$ 119.0
Vesting period of recognition of the unrecognized compensation cost of nonvested awards	1 year 8 months 12 days
Performance Stock Units (PSUs)
Stock compensation
Assumed annualized forfeiture rate (as a percent)	5.00%
Unrecognized compensation
Unrecognized compensation cost for nonvested option (in dollars)	$ 25.7
Vesting period of recognition of the unrecognized compensation cost of nonvested awards	1 year 3 months 18 days

Represents the expected annualized forfeiture rate for options granted.

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The weighted-average grant-date fair value of awards granted during the reporting period.

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Represents the amount of stock compensation expenses capitalized.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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Description of method used to estimate fair value of award under share-based payment arrangement.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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