Discontinued Operations - Assets and Liabilities of Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Carrying amounts of major classes of assets included as part of discontinued operations
Cash and cash equivalents	$ 0	$ 3,856	$ 2,982	$ 2,261
Total assets of discontinued operations	0	29,129
Carrying amounts of major classes of liabilities included as part of discontinued operations
Total liabilities of discontinued operations	$ 0	24,391
GovDelivery | Discontinued operations, held-for-sale
Carrying amounts of major classes of assets included as part of discontinued operations
Cash and cash equivalents		3,856
Accounts receivables, net of allowance		3,735
Fixed assets, net of accumulated depreciation and amortization		4,502
Goodwill		5,575
Intangible assets, net		8,952
Other assets included in the disposal group		2,509
Total assets of discontinued operations		29,129
Carrying amounts of major classes of liabilities included as part of discontinued operations
Accounts payable		3,309
Accrued expenses		2,764
Accrued compensation and benefits		2,386
Deferred revenue		14,180
Other liabilities included in the disposal group		1,752
Total liabilities of discontinued operations		$ 24,391