Summary of Short-Term Borrowings and Long-Term Debt (Parenthetical) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
2.875% Senior notes due October 1, 2022
Debt Instrument [Line Items]
Interest rate of debt	2.875%	2.875%
Maturity date of debt	Oct. 01, 2022	Oct. 01, 2022
3.35% Senior notes due December 15, 2015
Debt Instrument [Line Items]
Interest rate of debt	3.35%	3.35%
Maturity date of debt	Dec. 15, 2015	Dec. 15, 2015
2.45% Senior notes due December 15, 2019
Debt Instrument [Line Items]
Interest rate of debt	2.45%	2.45%
Maturity date of debt	Dec. 15, 2019	Dec. 15, 2019