Derivative Financial Instruments - Schedule of Interest Rate Derivatives (Details) - Interest rate swap - Fair Value Hedges	Mar. 31, 2016
1.35% senior note due 2018
Derivative [Line Items]
Fixed interest rate	1.35%
2.55% notes due 2020
Derivative [Line Items]
Fixed interest rate	2.55%
4.38% note due 2021
Derivative [Line Items]
Fixed interest rate	4.38%
3.70% notes due in 2023
Derivative [Line Items]
Fixed interest rate	3.70%
3.30% notes due 2024
Derivative [Line Items]
Fixed interest rate	3.30%
3.55% notes due 2025
Derivative [Line Items]
Fixed interest rate	3.55%
4.96% subordinated note due 2018
Derivative [Line Items]
Fixed interest rate	4.96%
3.10% subordinated note due 2023
Derivative [Line Items]
Fixed interest rate	3.10%