Earnings Per Share - Computations of Class A Basic and Diluted Earnings (Loss) per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from computation of earnings per share	8,600,000	8,100,000	400,000	8,500,000
Numerator for basic and diluted earnings per share:
Net earnings attributable to controlling interest	$ 32,718	$ 14,220	$ 168,640	$ 19,873
Less: earnings allocated to participating securities	(40)	(26)	(157)	(48)
Numerator for basic EPS - net income attributable to common stockholders	32,678	14,194	168,483	19,825
Add back allocation of earnings to participating securities	40	26	157	48
Add back convertible senior notes interest	0	0	7,480	0
Reallocation of earnings to participating securities considering potentially dilutive securities	(40)	(26)	(148)	(48)
Numerator for diluted earnings per share - net income attributable to common stockholders	$ 32,678	$ 14,194	$ 175,972	$ 19,825
Denominator for earnings per share:
Class A common stock - basic (in shares)	97,459,472	87,065,591	97,444,016	87,064,110
Class A common stock - diluted (in shares)	97,496,217	87,217,381	105,662,687	87,257,130
Calculation of basic and diluted earnings (loss) per share:
Basic (in dollars per share)	$ 0.34	$ 0.16	$ 1.73	$ 0.23
Diluted (in dollars per share)	0.34	0.16	1.67	0.23
Dividends declared per Class A common share (in dollars per share)	$ 0.42	$ 0.42	$ 0.84	$ 0.83
Stock options
Denominator for earnings per share:
Add dilutive effect (in shares)	0	7,488	0	0
Restricted stock awards
Denominator for earnings per share:
Add dilutive effect (in shares)	36,348	144,302	47,886	185,366
Restricted stock units
Denominator for earnings per share:
Add dilutive effect (in shares)	397	0	45	7,654
Convertible senior notes
Denominator for earnings per share:
Add dilutive effect (in shares)	0	0	8,170,740	0