Commitments and Contingencies (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) Aircraft
Types of Commercial Aircraft [Line Items]
Long-term Purchase Commitment, Minimum Quantity Required | Aircraft	25
Purchase Obligation, Future Minimum Payments, Remainder of Fiscal Year	$ 374,699
Unrecorded Unconditional Purchase Obligation, Minimum Quantity Required | Aircraft	38
Purchase Obligation, Due in Second Year	$ 143,855
Purchase Obligation, Due in Third Year	361,746
Purchase Obligation, Due in Fourth Year	277,819
Purchase Obligation, Due in Fifth Year	138,278
Purchase Obligation, Due after Fifth Year	0
Purchase Obligation	1,296,397
Pre-Delivery Payments [Member]
Types of Commercial Aircraft [Line Items]
Purchase Obligation	$ 127,767