Goodwill (Additional Information) (Details) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Impairment Loss, Net of Tax	$ 0	$ 0	$ 0

Amount after tax of loss recognized that results from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

No definition available.

Name:	us-gaap_GoodwillImpairmentLossNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration