Off-Balance Sheet Arrangements Commitments Guarantees and Contingencies (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments And Guarantees [Line Items]
Credit card guarantees	$ 8,400	$ 8,300
Fully collateralized credit card guarantees	1,200	975
Rent expense for operating leases	30,500	28,900	$ 28,900
Aggregate future minimum rentals to be received under non-cancelable subleases greater than one year	445
Partnership Interest of a Director [Member]
Commitments And Guarantees [Line Items]
Rent expense for operating leases	$ 1,400	$ 1,000	$ 963