Financial Instruments and Fair Value Measurements - Summary of Available-for-Sale Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Fair value of financial instruments owned, total	$ 50,495	$ 54,149
U.S. treasuries
Schedule Of Available For Sale Securities [Line Items]
Contractual maturities (less than)	3 years	3 years
Certificates of deposit
Schedule Of Available For Sale Securities [Line Items]
Contractual maturities (less than)	1 year	1 year
Level I \| U.S. treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 47,748	$ 51,376
Gross Unrealized Gains	13	25
Gross Unrealized Losses	(93)	(77)
Estimated Fair Value	47,668	51,324
Level I \| Mutual funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	500	500
Gross Unrealized Gains	7	5
Gross Unrealized Losses	0	0
Estimated Fair Value	507	505
Level I \| U.S. Treasuries & Mutual Funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	48,248	51,876
Gross Unrealized Gains	20	30
Gross Unrealized Losses	(93)	(77)
Estimated Fair Value	48,175	51,829
Level II \| Certificates of deposit
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,320	2,320
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 2,320	$ 2,320

Available for sale securities contractual maturity period.

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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-Publisher FASB
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-Topic 320
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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-Publisher FASB
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The aggregate fair value as of the balance sheet date of financial instruments and other positions owned by the entity including: (1) mortgages, mortgage-backed and asset backed securities; (2) US government and agency obligations; (3) state and municipal government obligations; (4) other sovereign government debt; (5) corporate obligations; (6) corporate equities; (7) principal investments; (8) derivative contracts; and (9) physical commodities. Includes both pledged and unpledged holdings.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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