Acquisitions - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended			12 Months Ended
	Feb. 28, 2018	Dec. 31, 2016	May 31, 2016	Dec. 31, 2016	Mar. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill					$ 60,929	$ 51,036
Twine Health, Inc. [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	$ 16,700
Goodwill	9,900
Deferred tax liabilities	1,600
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Deferred Revenue	200
Assumed liabilities	600
Consideration held as security for indemnifications obligations	2,600
Twine Health, Inc. [Member] | In Process Research and Development [Member]
Business Acquisition [Line Items]
Intangibles acquired	$ 5,400
Amortization period	4 years
Twine Health, Inc. [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Intangibles acquired	$ 3,800
Amortization period	7 years
Pebble Industries, Inc [Member]
Business Acquisition [Line Items]
Cash paid for acquisition		$ 23,400
Goodwill		14,400		$ 14,400
Assumed liabilities		600		600
Consideration held as security for indemnifications obligations		3,500
Pebble Industries, Inc [Member] | In Process Research and Development [Member]
Business Acquisition [Line Items]
Intangibles acquired		9,600		$ 9,600
Amortization period				5 years
Vector Watch S.R.L. [Member]
Business Acquisition [Line Items]
Cash paid for acquisition		15,000
Goodwill		11,400		$ 11,400
Assumed liabilities		300		300
Consideration held as security for indemnifications obligations		2,300
Vector Watch S.R.L. [Member] | In Process Research and Development [Member]
Business Acquisition [Line Items]
Intangibles acquired		$ 3,900		$ 3,900
Amortization period		2 years 6 months
Coin, Inc [Member]
Business Acquisition [Line Items]
Cash paid for acquisition			$ 7,000
Goodwill			3,100
Coin, Inc [Member] | In Process Research and Development [Member]
Business Acquisition [Line Items]
Intangibles acquired			$ 3,900