Discontinued Operations - Assets and Liabilities of Discontinued Operations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Carrying amounts of major classes of assets included as part of discontinued operations
Cash and cash equivalents	$ 4,876	$ 20,834	$ 21,961	$ 14,482
Less: assets of discontinued operations classified as non-current	0	192,017
Total assets of discontinued operations classified as current	181,084	166,505
Carrying amounts of major classes of liabilities included as part of discontinued operations
Less: liabilities of discontinued operations classified as non-current	0	27,917
Total liabilities of discontinued operations classified as current	19,826	50,907
GovDelivery | Discontinued operations, held-for-sale
Carrying amounts of major classes of assets included as part of discontinued operations
Cash and cash equivalents	4,876	20,834
Accounts receivables, net of allowance	7,260	21,033
Fixed assets, net of accumulated depreciation and amortization	927	5,266
Goodwill	136,251	231,787
Intangible assets, net	30,343	72,706
Other assets included in the disposal group	1,427	6,896
Total assets of discontinued operations	181,084	358,522
Less: assets of discontinued operations classified as non-current	0	192,017
Total assets of discontinued operations classified as current	181,084	166,505
Carrying amounts of major classes of liabilities included as part of discontinued operations
Accounts payable	5,312	11,161
Accrued expenses	2,869	8,415
Accrued compensation and benefits	2,957	7,671
Deferred revenue	2,371	36,824
Other liabilities included in the disposal group	6,317	14,753
Total liabilities of discontinued operations	19,826	78,824
Less: liabilities of discontinued operations classified as non-current	0	27,917
Total liabilities of discontinued operations classified as current	$ 19,826	$ 50,907