Organization and Summary of Significant Accounting Policies - Narrative (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2020	Dec. 31, 2021 USD ($) reporting_unit segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Accounting Policies [Line Items]
Number of operating segments | segment		1
Number of reporting segments | segment		1
Deferred revenues, net of cost of goods sold		$ 132,390,000	$ 105,726,000
Deferred revenues, net of cost of goods sold, expected to be completed within one year		$ 112,196,000	100,053,000
Recognition period		five years
Fees to GPOs		$ 17,500,000	9,700,000	$ 11,100,000
Amortization period for capitalized contract costs		10 years
Initial term and renewal service periods		10 years
Contract cost expense		$ 25,800,000	22,100,000	24,400,000
Impairment loss related to capitalized prepaid commissions		$ 0
Operating lease renewal terms		1 year
Non-recourse accounts receivable transferred		$ 46,700,000	58,800,000	48,300,000
Accounts receivable due from third-party leasing companies for transferred non-recourse accounts receivable		5,600,000	7,800,000
Cash and cash equivalents		349,051,000	485,928,000	127,210,000
Cash equivalents		320,200,000	447,200,000
Minimum required purchase obligation		170,100,000
Cost of revenues		577,365,000	478,916,000	460,115,000
Amortization of capitalized software development costs		$ 26,400,000	23,100,000	$ 17,500,000
Number of reporting units | reporting_unit		1
Accumulated impairment loss on goodwill		$ 0
Accounting Standards Update [Extensible List]	Accounting Standards Update 2020-06 [Member]			Accounting Standards Update 2016-13 [Member]
Convertible senior notes, net		0	467,201,000
Additional paid-in capital		1,024,580,000	920,359,000
Long-term deferred tax liabilities		51,705,000	39,633,000
Long-term deferred tax assets		15,883,000	15,019,000
Retained earnings		368,571,000	290,722,000
Cumulative Effect of a Change in Accounting Principle
Accounting Policies [Line Items]
Convertible senior notes, net		75,400,000
Additional paid-in capital		72,700,000
Long-term deferred tax liabilities		19,800,000
Long-term deferred tax assets		500,000
Retained earnings		16,700,000
Other Assets
Accounting Policies [Line Items]
Software development costs capitalized		$ 29,400,000	32,000,000
Internal Use Software and Software Development Costs
Accounting Policies [Line Items]
Useful life of property and equipment		5 years
Internal Use Software and Software Development Costs | Property and Equipment
Accounting Policies [Line Items]
Software development costs capitalized		$ 12,700,000	6,800,000
Shipping Costs | Selling, general, and administrative
Accounting Policies [Line Items]
Cost of revenues		18,200,000	15,600,000	$ 15,900,000
Primary Supplier
Accounting Policies [Line Items]
Minimum required purchase obligation		$ 0
Period for notice of termination		6 months
Purchases from suppliers		$ 103,200,000	$ 76,300,000	$ 75,100,000
Minimum
Accounting Policies [Line Items]
Original terms of contracts		1 year
Maximum
Accounting Policies [Line Items]
Original terms of contracts		5 years
Estimated useful life of software-related products		5 years
Customer Concentration Risk | Revenues | Ten Largest GPOs
Accounting Policies [Line Items]
Concentration risk percentage		67.00%
Customer Concentration Risk | Lease Receivable | U.S. Government Hospitals
Accounting Policies [Line Items]
Concentration risk percentage		69.00%