Summary Of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2020	Jul. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Stock options, outstanding	696,711	957,559
Stock options, weighted average exercise price	$ 43.88	$ 30.81
Common stock excluded from calculation of diluted earnings per share	98,048	104,316		479,854
Convertible senior notes	366,534	1,123,139	1,123,000
Advertising Expense	$ 300,000	$ 100,000	$ 200,000
Cash and cash equivalents	717,292,000	528,392,000	$ 193,822,000
Restricted Cash		$ 9,000,000.0			$ 9,000,000.0
Accounts Receivable [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Risk, Percentage		10.00%
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents	$ 549,000,000.0	$ 415,600,000
0.375% Convertible Senior Notes due 2024
Summary Of Significant Accounting Policies [Line Items]
Principal amount						$ 287,500,000
Notes, frequency of periodic payment	semi-annually
Total convertible senior notes						501,000,000.0
Fair value of convertible senior notes						$ 243,700,000
Senior convertible notes		0.375%				0.375%
Awards Granted to Executive Level Employees
Summary Of Significant Accounting Policies [Line Items]
Estimated forfeiture rates	3.00%
Awards Granted to Non-Executive Level Employees
Summary Of Significant Accounting Policies [Line Items]
Estimated forfeiture rates	8.00%
Option To Purchase Common Stock
Summary Of Significant Accounting Policies [Line Items]
Stock options, outstanding	696,711	957,559	998,226
Stock options, weighted average exercise price		$ 30.81	$ 27.54
Restricted Stock Units (RSUs)
Summary Of Significant Accounting Policies [Line Items]
Restricted stock units, outstanding	665,540	734,984	705,413
Non-Employee Directors
Summary Of Significant Accounting Policies [Line Items]
Estimated forfeiture rates	0.00%
Employee Stock Option [Member] | Awards Granted to Executive Level Employees
Summary Of Significant Accounting Policies [Line Items]
Estimated forfeiture rates	3.00%
Employee Stock Option [Member] | Awards Granted to Non-Executive Level Employees
Summary Of Significant Accounting Policies [Line Items]
Estimated forfeiture rates	8.00%
Cytiva [Member] | Accounts Receivable [Member] | Customer Concentration Risk [Member]
Summary Of Significant Accounting Policies [Line Items]
Concentration Risk, Percentage	11.00%	18.00%