Summary of Significant Accounting Policies - Property and Equipment and Capitalized Software Cost (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	$ 29,377	$ 26,905
Depreciation and amortization expense	2,796	2,919	2,271
Minimum
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, useful life	1 year
Capitalized computer software amortization period	2 years
Maximum
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, useful life	30 years
Capitalized computer software amortization period	5 years
Capitalized Software [Member]
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, gross	6,774	5,088
Depreciation and amortization expense	$ 1,200	$ 1,700	$ 1,100
Capitalized Software [Member] | Minimum
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, useful life	2 years
Capitalized Software [Member] | Maximum
Property, Plant and Equipment [Line Items]
Property, equipment and capitalized software, useful life	5 years