Internal Use Software Development Costs (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Research and Development [Abstract]
Capitalized computer software, additions	$ 9,200,000	$ 9,400,000	$ 4,100,000
Capitalized computer software, amortization	6,700,000	5,100,000	2,700,000
Internal use software development costs, write-offs	1,500,000	700,000	200,000
Estimated amortization expense, 2016	6,500,000
Estimated amortization expense, 2017	4,900,000
Estimated amortization expense, 2018	2,400,000
Estimated amortization expense, 2019	200,000
Capitalized computer software, impairments	$ 0	$ 0	$ 0