The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

+ Details

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- Definition

Number of seats on the governing board.

+ References

No definition available.

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- Definition

Schedule Of Investments In Joint Venture [Line Items]

+ References

No definition available.

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Investments in Joint Ventures - S & I Ophthalmic - Additional Information (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2013 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) board_seat
Schedule Of Investments In Joint Venture [Line Items]
Investment		$ 9,977,000	$ 23,655,000
S & I Ophthalmic, LLC
Schedule Of Investments In Joint Venture [Line Items]
Capital contribution	$ 5,000,000	5,000,000
Membership interest	50.00%
Total number of seats on the joint venture's governing board \| board_seat			4
Investor \| S & I Ophthalmic, LLC
Schedule Of Investments In Joint Venture [Line Items]
Capital contribution	$ 5,000,000	5,000,000
Membership interest	50.00%
Investments in affiliates \| S & I Ophthalmic, LLC
Schedule Of Investments In Joint Venture [Line Items]
Investment		$ 6,379,000	$ 3,236,000