Reconciliation of Segment Income from Operations to Income before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting [Abstract]
Total segment income from operations	$ 319,812	$ 360,853	$ 324,180
Interest and other debt expense	66,926	76,301	69,462
Income before income taxes	$ 252,886	$ 284,552	$ 254,718