Income Taxes - Reconciliation of Tax Provision for Continuing Operations (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016 Rate	Dec. 31, 2015	Dec. 31, 2015 Rate	Dec. 31, 2014	Dec. 31, 2014 Rate
Income Tax Disclosure [Abstract]
Tax provision at U.S. statutory rate		35.00%		35.00%		35.00%
Tax exempt interest		(5.20%)		(6.70%)		(10.30%)
Audit settlements & unrecognized tax benefits		(5.20%)		(5.00%)		0.90%
Tax on undistributed foreign earnings		4.90%		(5.60%)		(8.10%)
U.S. tax on foreign earnings		4.70%		3.80%		9.30%
Foreign tax rate differential		(3.50%)		(3.60%)		(6.20%)
U.S. permanent items		(1.90%)		(1.00%)		(1.00%)
Valuation allowance on deferred tax assets		1.40%		2.10%		8.60%
Other adjustments		(0.70%)		(0.60%)		(1.30%)
State and local income tax		(0.10%)		1.00%		1.60%
Foreign tax holiday		0.00%		(1.10%)		(1.30%)
Effective income tax rate	29.40%	29.40%	18.30%	18.30%	27.20%	27.20%