Derivative Financial Instruments - Contractual and Weighted-Average Interest Rates, Which Include the Effects of Hedges Related to Financial Instruments (Details) - Long-term debt	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative [Line Items]
Contractual rates	3.37%	3.59%	3.41%	3.60%
Rate including impact of hedges	2.27%	2.35%	2.24%	2.51%