Off-Balance Sheet Arrangements Commitments Guarantees and Contingencies (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments And Guarantees [Line Items]
Credit card guarantees	$ 8,900,000	$ 8,400,000
Fully collateralized credit card guarantees	1,500,000	1,200,000
Minimum percentage of collateral required for securities borrowed	100.00%
Maximum future payments guaranteed	2,500,000,000
Held in trust liquid assets as collateral	2,500,000,000
Rent expense for operating leases	28,200,000	24,600,000	22,700,000
Aggregate future minimum rentals to be received under non-cancelable subleases greater than one year	209,000
Partnership Interest of a Director [Member]
Commitments And Guarantees [Line Items]
Rent expense for operating leases	$ 925,000	$ 871,000	$ 902,000