Long-Term Debt (Details 2) - Senior Notes [Member]	12 Months Ended
	Dec. 31, 2018
Senior unsecured notes due 2022 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	102.813%
Senior unsecured notes due 2022 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	101.406%
Senior unsecured notes due 2022 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	100.00%
Senior unsecured notes due 2023 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	102.813%
Senior unsecured notes due 2023 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	101.406%
Senior unsecured notes due 2023 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	100.00%
Senior Unsecured Notes due 2025 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	103.188%
Senior Unsecured Notes due 2025 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	101.594%
Senior Unsecured Notes due 2025 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	100.00%
Senior unsecured notes due 2026 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	103.625%
Senior unsecured notes due 2026 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	101.813%
Senior unsecured notes due 2026 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument, Redemption [Line Items]
Early redemption premium	100.00%