XML 44 R21.htm IDEA: XBRL DOCUMENT
v3.8.0.1

401(k) savings plan | 12 Months Ended
--- | ---
Dec. 31, 2017
401(k) savings plan [Abstract] |
401(k) savings plan | 13. 401(k) savings plan The Company has established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. The 401(k) Plan covers substantially all U.S. employees. Under the 401(k) Plan, employees may make elective salary deferrals. The Company currently provides for matching of qualified deferrals up to 50% of the first 6% of the employee's salary. During the years ended December 31, 2017, 2016, and 2015, the Company made matching contributions of approximately $2.7 million, $2.5 million and $2.2 million, respectively.

X
- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for pension and other postretirement benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -URI http://asc.fasb.org/topic&trid=2235017 + Details
Name: | us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration