Reconciliation of Segment Income from Operations to Income before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting [Abstract]
Total segment income from operations	$ 299,730	$ 319,812	$ 360,853
Interest and other debt expense	67,813	66,926	76,301
Income before income taxes	$ 231,917	$ 252,886	$ 284,552