Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 17,609,000	$ 20,437,000	$ 22,501,000
Stock-based compensation capitalized as software development costs (2016 - less than)	0	0	0
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	1,475,000	1,371,000	2,670,000
Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	16,134,000	19,066,000	19,831,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	9,008,000	15,487,000	15,647,000
Performance-based stock options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	447,000	447,000	374,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	7,766,000	4,503,000	2,583,000
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	388,000	0	0
Acceleration of unvested equity awards
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 0	$ 0	$ 3,897,000