Debt - Rating Agencies interest rate (Details)	6 Months Ended
	Jun. 30, 2019
Maximum
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	2.00%
BB Plus
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	0.25%
BB
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	0.50%
BB-
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	0.75%
B Plus Or Below
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	1.00%
Ba1
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	0.25%
Ba2
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	0.50%
Ba3
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	0.75%
B1 or below
Financing Receivable, Recorded Investment [Line Items]
Interest rate increase	1.00%