Stockholders' Equity - Net Income Attributable to Noncontrolling Interests (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Change In Ownership Interest [Line Items]
Net Income Attributable to Noncontrolling Interests	$ 2,877	$ 3,900
Noncontrolling interests	60,110		$ 57,826
Edgewater [Member]
Change In Ownership Interest [Line Items]
Net Income Attributable to Noncontrolling Interests	2,877	$ 3,900
Noncontrolling interests	59,533		57,238
Other [Member]
Change In Ownership Interest [Line Items]
Noncontrolling interests	$ 577		$ 588