Investments - Schedule of Investments (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Equity Method Investment Balances [Roll Forward]
Investment in WMES joint ventures at beginning of the period	$ 57,936	$ 47,941
Earnings from joint ventures	2,642	8,578
Contribution	0	5,713
Distribution	(7,200)	(3,300)
Foreign currency translation adjustment	(1,018)	222
Unrealized loss on derivative instruments at joint venture	(1,121)	(774)
Investment in WMES joint ventures at end of the period	53,275	57,936
WMES
Equity Method Investment Balances [Roll Forward]
Investment in WMES joint ventures at beginning of the period	44,134	34,183
Earnings from joint ventures	1,552	8,312
Contribution	0	5,713
Distribution	(7,200)	(3,300)
Foreign currency translation adjustment	0	0
Unrealized loss on derivative instruments at joint venture	(1,121)	(774)
Investment in WMES joint ventures at end of the period	37,365	44,134
CASC Willis
Equity Method Investment Balances [Roll Forward]
Investment in WMES joint ventures at beginning of the period	13,802	13,758
Earnings from joint ventures	1,090	266
Contribution	0	0
Distribution	0	0
Foreign currency translation adjustment	(1,018)	222
Unrealized loss on derivative instruments at joint venture	0	0
Investment in WMES joint ventures at end of the period	$ 15,910	$ 13,802

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.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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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.

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The cash inflow from the sale of an investment interest in a joint venture that the reporting entity has not previously accounted for using consolidation or the equity method of accounting.

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