Changes in Goodwill (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Goodwill [Roll Forward]    
Goodwill $ 1,583,564 $ 1,586,482
Accumulated impairment losses (329,741) (329,741)
Beginning Balance, Subtotal 1,253,823 1,256,741
Acquisitions 0 886
Purchase price allocation adjustments 371 (3,188)
Disposition (1,129) (616)
Impairment losses (549,711) 0
Goodwill 1,582,806 1,583,564
Accumulated impairment losses (879,452) (329,741)
Ending Balance, Subtotal $ 703,354 $ 1,253,823