Debt - Line of Credit (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Available Additional Borrowing Capacity	$ 300.0
Payments of Financing Costs	$ 2.2
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.125%
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.30%
Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 500.0
Credit Agreement [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 300.0
Credit Agreement [Member] | Adjusted Base Rate Advances [Member] | Adjusted Base Rate [Member] | Federal Funds Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Basis Spread on Variable Rate	0.50%
Credit Agreement [Member] | Adjusted Base Rate Advances [Member] | Adjusted Base Rate [Member] | Eurodollar Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Basis Spread on Variable Rate	1.00%
Credit Agreement [Member] | Adjusted Base Rate Advances [Member] | Applicable Margin [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Basis Spread on Variable Rate	0.125%
oii term loan facility spread on variable rate	0.00%
Credit Agreement [Member] | Adjusted Base Rate Advances [Member] | Applicable Margin [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Basis Spread on Variable Rate	0.75%
oii term loan facility spread on variable rate	0.50%
Credit Agreement [Member] | Eurodollar Advances [Member] | Applicable Margin [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Basis Spread on Variable Rate	1.125%
oii term loan facility spread on variable rate	1.00%
Credit Agreement [Member] | Eurodollar Advances [Member] | Applicable Margin [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Basis Spread on Variable Rate	1.75%
oii term loan facility spread on variable rate	1.50%