General - Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets
Restricted cash and cash equivalents	$ 73,272	$ 81,776
Investments	313,700	305,253
Cash held in bank accounts	160,600	127,000
Liabilities
Contingent consideration	11,104	11,153
Level 2 \| Term Loan
Liabilities
Fair value of debt	612,500
Fair value measured on recurring basis
Assets
Total assets held at fair value	426,680	482,748
Liabilities
Contingent consideration	11,104	11,153
Total liabilities held at fair value	11,104	11,153
Fair value measured on recurring basis \| Other than cash held in bank accounts by Company
Assets
Cash and cash equivalents	112,980	177,495
Fair value measured on recurring basis \| U.S. Government and agency securities
Assets
Investments	5,704	5,817
Fair value measured on recurring basis \| Obligations of government-sponsored enterprises
Assets
Investments	28,110	25,767
Fair value measured on recurring basis \| Corporate debt securities
Assets
Investments	273,391	272,219
Fair value measured on recurring basis \| Certificates of deposit
Assets
Investments	1,450	1,450
Fair value measured on recurring basis \| Taxable municipal bonds
Assets
Investments	5,045
Fair value measured on recurring basis \| Level 1
Assets
Total assets held at fair value	5,704	5,817
Fair value measured on recurring basis \| Level 1 \| U.S. Government and agency securities
Assets
Investments	5,704	5,817
Fair value measured on recurring basis \| Level 2
Assets
Total assets held at fair value	420,976	476,931
Fair value measured on recurring basis \| Level 2 \| Other than cash held in bank accounts by Company
Assets
Cash and cash equivalents	112,980	177,495
Fair value measured on recurring basis \| Level 2 \| Obligations of government-sponsored enterprises
Assets
Investments	28,110	25,767
Fair value measured on recurring basis \| Level 2 \| Corporate debt securities
Assets
Investments	273,391	272,219
Fair value measured on recurring basis \| Level 2 \| Certificates of deposit
Assets
Investments	1,450	1,450
Fair value measured on recurring basis \| Level 2 \| Taxable municipal bonds
Assets
Investments	5,045
Fair value measured on recurring basis \| Level 3
Liabilities
Contingent consideration	11,104	11,153
Total liabilities held at fair value	$ 11,104	$ 11,153

Fair value of contingent consideration in a business combination as of the balance sheet date.

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=6506951

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Fair value of financial and nonfinancial obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

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