Organization and Summary of Significant Accounting Policies - Narative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019	Oct. 01, 2018
Accounting Policies [Line Items]
Percent fair value exceeds carrying value					41.00%
Gross profit	$ 35,616,000	$ 4,512,000	$ 12,976,000
Net income	37,729,000	30,518,000	9,756,000
Revenues	787,309,000	712,714,000	695,908,000
Selling, general, and administrative	(263,095,000)	(241,470,000)	(237,881,000)
Contract with Customer, Liability	92,417,000	89,397,000
Deferred revenues, net	81,835,000	78,774,000
Fees to GPOs	8,700,000	7,400,000	8,400,000
Deferred Revenues Recognized	85,700,000
Deferred Revenue Current, Gross		95,700,000
Capitalized Commissions	21,100,000	17,900,000	18,800,000
Impairment Loss	0
Purchase Obligation	52,200,000
Sales-type Lease, Revenue	39,200,000	29,600,000	34,900,000
Transferred non-recourse accounts receivables	46,600,000	40,000,000	28,700,000
Accounts receivables from third-party leasing companies for transferred non-recourse accounts receivables	10,600,000	100,000	200,000
Depreciation and amortization	15,100,000	16,200,000	15,000,000
Total cost of revenues	$ 414,979,000	394,077,000	378,823,000
Internal use software and development costs
Accounting Policies [Line Items]
Useful life (in years)	5 years
Software and development costs to be sold
Accounting Policies [Line Items]
Cost of revenues for amortization of capitalized software development cost	$ 12,500,000	9,700,000	7,100,000
Min
Accounting Policies [Line Items]
Estimated useful lives of assets (in years)	1 year
Max
Accounting Policies [Line Items]
Estimated useful lives of assets (in years)	30 years
Max | Internal use software and development costs
Accounting Policies [Line Items]
Useful life (in years)	5 years
Max | Min
Accounting Policies [Line Items]
Useful life (in years)	3 years
Capitalized software costs included in property and equipment | Internal use software and development costs
Accounting Policies [Line Items]
Software development costs capitalized	$ 1,100,000	400,000
Capitalized software costs included in other assets | Software and development costs to be sold
Accounting Policies [Line Items]
Software development costs capitalized	30,700,000	15,000,000
Primary Supplier
Accounting Policies [Line Items]
Purchase Obligation	$ 0
Notice of termination, time upon delivery (in months)	2 months
Payments to suppliers	$ 54,800,000	64,500,000	47,900,000
International Subsidiaries Business Acquisitions
Accounting Policies [Line Items]
Selling, general, and administrative	$ 2,600,000
Revolving Credit Facility
Accounting Policies [Line Items]
Debt instrument, term (in years)	5 years
Term Loan Facility
Accounting Policies [Line Items]
Debt instrument, term (in years)	5 years
Product revenues
Accounting Policies [Line Items]
Total cost of revenues	$ 312,360,000	304,842,000	302,437,000
Product revenues | Difference between Revenue Guidance in Effect before and after Topic 606
Accounting Policies [Line Items]
Revenues		800,000
Shipping and handling | Selling, general and administrative
Accounting Policies [Line Items]
Total cost of revenues	14,100,000	13,600,000	$ 12,100,000
Foreign Exchange Forward
Accounting Policies [Line Items]
Derivative, Notional Amount	$ 0	$ 0
U.S. Government Hospitals | Customer Concentration Risk | Lease Receivable
Accounting Policies [Line Items]
Concentration risk percentage	49.00%
Group Purchasing Organizations | Professional Services [Member] | Customer Concentration Risk
Accounting Policies [Line Items]
Concentration risk percentage	58.80%
Adjustment
Accounting Policies [Line Items]
Gross profit	$ 3,200,000
Net income	$ 2,500,000
Subsequent event | ASU 842 - Leases
Accounting Policies [Line Items]
Operating lease, right-of-use asset				$ 66,000,000
Operating lease, liability				$ 70,000,000