Aggregate dividends declared during the period for each share of common stock outstanding.

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Date the declared dividend will be paid, in CCYY-MM-DD format.

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Amount of paid and unpaid cash, stock, and paid-in-kind (PIK) dividends declared, for example, but not limited to, common and preferred stock.

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Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding.

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Date the dividend to be paid was declared, in CCYY-MM-DD format.

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Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

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No definition available.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands						1 Months Ended								3 Months Ended		9 Months Ended
	Sep. 12, 2019	Sep. 14, 2018	Aug. 14, 2018	May 15, 2018	Feb. 28, 2018	May 30, 2019	Mar. 29, 2019	Feb. 26, 2019	Jan. 04, 2019	Nov. 28, 2018	Jun. 22, 2018	Mar. 30, 2018	Feb. 28, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Common Stock, Dividends, Per Share, Declared														$ 0.30	$ 0.30	$ 0.90	$ 0.90
Dividends Payable, Date to be Paid			Sep. 14, 2018	Jun. 22, 2018	Mar. 30, 2018			Mar. 29, 2019		Jan. 04, 2019
Dividends Payable, Date of Record		Aug. 31, 2018					Mar. 12, 2019		Dec. 10, 2018		May 31, 2018	Mar. 12, 2018
Dividends	$ 1,800					$ 1,800	$ 1,800
Dividends Payable		$ 1,800										$ 1,800
Payments of Ordinary Dividends, Common Stock									$ 3,300		$ 1,800					$ 6,842	$ 11,864
Dividends Payable, Date Declared			Aug. 14, 2018	May 15, 2018				Feb. 26, 2019		Nov. 28, 2018			Feb. 28, 2018
Class A Common Stock
Common Stock, Dividends, Per Share, Declared	$ 0.30		$ 0.30	$ 0.30		$ 0.30		$ 0.30		$ 0.30			$ 0.30
Class B Common Stock
Common Stock, Dividends, Per Share, Declared			$ 0.30	$ 0.30				$ 0.30		$ 0.25			$ 0.30