Commitments and Contingencies - Unfunded Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Due in less than one year	$ 293,382	$ 312,152
Due within one to three years	0	1,090
Total	$ 293,382	$ 313,242

Minimum amount of other commitment maturing in the second and third fiscal years following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

Name:	us-gaap_OtherCommitmentDueInSecondAndThirdYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant