Equity Method Investments - Activity Related to Equity Method Investments (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Equity Method Investments
Balance at beginning of period	$ 129,524	$ 103,517
Contributions	7,742	11,652
Earnings (loss) on equity method investments	(1,283)	2,009
Balance at end of period	$ 135,983	117,178
Constitution
Schedule of Equity Method Investments [Line Items]
Ownership percentage	25.00%
Equity Method Investments
Balance at beginning of period	$ 96,850	90,345
Contributions	1,125	6,250
Earnings (loss) on equity method investments	(1,282)	2,011
Balance at end of period	96,693	98,606
Contributions to date	$ 89,700
Meade
Schedule of Equity Method Investments [Line Items]
Ownership percentage	20.00%
Equity Method Investments
Balance at beginning of period	$ 32,674	13,172
Contributions	6,617	5,402
Earnings (loss) on equity method investments	(1)	(2)
Balance at end of period	39,290	$ 18,572
Investment Commitment
Equity Method Investments
Expected future contributions	70,000
Investment Commitment \| Constitution
Equity Method Investments
Anticipated contributions	$ 240,000

Equity Method Investment, Contributions to Date

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Equity Method Investments [Roll Forward]

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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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

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Amount of other commitments maturing in the remainder of the fiscal year following the latest fiscal year ended.

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The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

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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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