Long-term Debt - Debt Instrument Redemption Percentages (Details) - Senior notes [Member]	Dec. 15, 2019	May 15, 2015
Redemption Period 1 [Member]
Debt Instrument [Line Items]
Redemption price percentages		104.063%
Redemption Period 1 [Member] | Forecast [Member]
Debt Instrument [Line Items]
Redemption price percentages	105.50%
Redemption Period 2 [Member]
Debt Instrument [Line Items]
Redemption price percentages		102.031%
Redemption Period 2 [Member] | Forecast [Member]
Debt Instrument [Line Items]
Redemption price percentages	103.50%
Redemption Period 3 [Member]
Debt Instrument [Line Items]
Redemption price percentages		100.00%
Redemption Period 3 [Member] | Forecast [Member]
Debt Instrument [Line Items]
Redemption price percentages	100.00%