Investments in Joint Ventures - S & I Ophthalmic - Additional Information (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2013 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2017 USD ($) board_seat	Dec. 31, 2016 USD ($)
Schedule of Equity Method Investments [Line Items]
Investment			$ 21,904	$ 23,655
S & I Ophthalmic, LLC
Schedule of Equity Method Investments [Line Items]
Capital contributions	$ 5,000	$ 5,000
Membership interest	50.00%
Total number of seats on the joint venture's governing board | board_seat			4
Total number of seats on the joint venture's governing board, internally selected | board_seat			2
Total number of seats on the joint venture's governing board, externally selected | board_seat			2,000
S & I Ophthalmic, LLC | Investors
Schedule of Equity Method Investments [Line Items]
Capital contributions	$ 5,000	$ 5,000
Membership interest	50.00%
S & I Ophthalmic, LLC | Investments In Affiliates
Schedule of Equity Method Investments [Line Items]
Investment			$ 2,767	$ 3,236