Calculations of Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic Loss per Common Share:
(Loss) income from continuing operations, net of tax	$ 10,187	$ (17,462)	$ (143,011)	$ (8,565)					$ (158,851)	$ 3,030	$ (2,056)
Less: Net income attributable to non-controlling interests	1,918	(163)	264	(453)	$ (4)	$ (151)	$ 87	$ (78)	1,566	(146)	(170)
Less: Accretion of redemption preference on redeemable convertible non-controlling interest - Netsmart	(10,963)	(10,962)	(10,963)	(10,962)	(10,192)	(10,191)	(8,153)	0	(43,850)	(28,536)	0
Net loss from continuing operations attributable to Allscripts Healthcare Solutions, Inc. stockholders									(201,135)	(25,652)	(2,226)
Net income from discontinued operations attributable to Allscripts Healthcare Solutions, Inc. stockholders									4,676	0	0
Net loss attributable to Allscripts Healthcare Solutions, Inc. stockholders	$ 5,818	$ (28,587)	$ (153,710)	$ (19,980)	(7,314)	(10,185)	(10,202)	2,049	$ (196,459)	$ (25,652)	$ (2,226)
Weighted-average common shares outstanding									180,830	186,188	185,082
Continuing operations	$ 0.00	$ (0.16)	$ (0.85)	$ (0.11)					$ (1.12)	$ (0.14)	$ (0.01)
Discontinued operations	0.03	0.00	0.00	0.00					0.03	0.00	0.00
Net (loss) income attributable to Allscripts Healthcare Solutions, Inc. stockholders per share	$ 0.03	$ (0.16)	$ (0.85)	$ (0.11)					$ (1.09)	$ (0.14)	$ (0.01)
Diluted Loss per Common Share:
(Loss) income from continuing operations, net of tax									$ (158,851)	$ 3,030	$ (2,056)
Less: Net income attributable to non-controlling interests	$ 1,918	$ (163)	$ 264	$ (453)	(4)	(151)	87	(78)	1,566	(146)	(170)
Less: Accretion of redemption preference on redeemable convertible non-controlling interest - Netsmart	(10,963)	(10,962)	(10,963)	(10,962)	(10,192)	(10,191)	(8,153)	0	(43,850)	(28,536)	0
Net loss from continuing operations attributable to Allscripts Healthcare Solutions, Inc. stockholders									(201,135)	(25,652)	(2,226)
Net income from discontinued operations attributable to Allscripts Healthcare Solutions, Inc. stockholders									4,676	0	0
Net loss attributable to Allscripts Healthcare Solutions, Inc. stockholders	$ 5,818	$ (28,587)	$ (153,710)	$ (19,980)	$ (7,314)	$ (10,185)	$ (10,202)	$ 2,049	$ (196,459)	$ (25,652)	$ (2,226)
Weighted-average common shares outstanding									180,830	186,188	185,082
Dilutive effect of stock options, restricted stock unit awards and warrants									0	0	0
Weighted-average common shares outstanding assuming dilution									180,830	186,188	185,082
Continuing operations	$ 0.00	$ (0.16)	$ (0.85)	$ (0.11)					$ (1.12)	$ (0.14)	$ (0.01)
Discontinued operations	0.03	0.00	0.00	0.00					0.03	0.00	0.00
Net (loss) income attributable to Allscripts Healthcare Solutions, Inc. stockholders per share	$ 0.03	$ (0.16)	$ (0.85)	$ (0.11)					$ (1.09)	$ (0.14)	$ (0.01)