Borrowings (Schedule of Borrowings 1) (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
4.2% Senior Notes, due December 2021
Debt Instrument [Line Items]
Stated interest rate	4.20%
Senior Notes, maturity date	2021-12	2021-12
4.5% Senior Notes, due December 2020
Debt Instrument [Line Items]
Stated interest rate	4.50%
Senior Notes, maturity date	2020-12	2020-12