Supplemental Guarantor Condensed Consolidated Financial Statements - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operations:
Cash provided by (used in) operating activities	$ 11,311	$ (70,385)
Cash flows from investing activities
Purchase of furniture, equipment and leasehold improvements	(3,947)	(2,075)
Proceeds from settlement of company-owned life insurance	0	1,194
Purchase of tangible assets	(400)	0
Cash used in investing activities	(4,347)	(881)
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	(2,913)	(2,940)
Cash dividends paid to non-controlling interest	0	(816)
Payments for Repurchase of Common Stock	0	(5,159)
Payments for employee taxes withheld related to vested share-based awards	(2,444)	(2,203)
Proceeds from Issuance of Long-term Debt		(200,000)
Repayments of Long-term Debt		(150,000)
Payments of Debt Issuance Costs	0	(547)
Redemption of senior secured notes	(10,800)	84,600
Cash (used in) provided by financing activities	(16,157)	122,935
Net (decrease) increase in cash and cash equivalents	(9,193)	51,669
Cash and cash equivalents, beginning of period	48,154	64,913
Cash and cash equivalents, end of period	38,961	116,582
Eliminations
Cash flows from operations:
Cash provided by (used in) operating activities	0	0
Cash flows from investing activities
Purchase of furniture, equipment and leasehold improvements	0	0
Proceeds from settlement of company-owned life insurance		0
Purchase of tangible assets	0
Cash used in investing activities	0	0
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	0	0
Cash dividends paid to non-controlling interest		0
Payments for Repurchase of Common Stock		0
Payments for employee taxes withheld related to vested share-based awards	0	0
Proceeds from Issuance of Long-term Debt		0
Repayments of Long-term Debt		0
Payments of Debt Issuance Costs		0
Redemption of senior secured notes	0	0
Cash (used in) provided by financing activities	0	0
Net (decrease) increase in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Guarantor Subsidiaries
Cash flows from operations:
Cash provided by (used in) operating activities	1,272	(7,052)
Cash flows from investing activities
Purchase of furniture, equipment and leasehold improvements	0	0
Proceeds from settlement of company-owned life insurance		0
Purchase of tangible assets	(400)
Cash used in investing activities	(400)	0
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	0	0
Cash dividends paid to non-controlling interest		0
Payments for Repurchase of Common Stock		0
Payments for employee taxes withheld related to vested share-based awards	0	0
Proceeds from Issuance of Long-term Debt		0
Repayments of Long-term Debt		0
Payments of Debt Issuance Costs		0
Redemption of senior secured notes	0	0
Cash (used in) provided by financing activities	0	0
Net (decrease) increase in cash and cash equivalents	872	(7,052)
Cash and cash equivalents, beginning of period	3,716	10,284
Cash and cash equivalents, end of period	4,588	3,232
Non-Guarantor Subsidiaries
Cash flows from operations:
Cash provided by (used in) operating activities	11,456	(97,606)
Cash flows from investing activities
Purchase of furniture, equipment and leasehold improvements	(3,947)	(2,075)
Proceeds from settlement of company-owned life insurance		1,194
Purchase of tangible assets	0
Cash used in investing activities	(3,947)	(881)
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	0	0
Cash dividends paid to non-controlling interest		(816)
Payments for Repurchase of Common Stock		0
Payments for employee taxes withheld related to vested share-based awards	0	0
Proceeds from Issuance of Long-term Debt		0
Repayments of Long-term Debt		0
Payments of Debt Issuance Costs		0
Redemption of senior secured notes	(10,800)	84,600
Cash (used in) provided by financing activities	(10,800)	83,784
Net (decrease) increase in cash and cash equivalents	(3,291)	(14,703)
Cash and cash equivalents, beginning of period	36,996	54,400
Cash and cash equivalents, end of period	33,705	39,697
Parent
Cash flows from operations:
Cash provided by (used in) operating activities	(1,417)	34,273
Cash flows from investing activities
Purchase of furniture, equipment and leasehold improvements	0	0
Proceeds from settlement of company-owned life insurance		0
Purchase of tangible assets	0
Cash used in investing activities	0	0
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	(2,913)	(2,940)
Cash dividends paid to non-controlling interest		0
Payments for Repurchase of Common Stock		(5,159)
Payments for employee taxes withheld related to vested share-based awards	(2,444)	(2,203)
Proceeds from Issuance of Long-term Debt		200,000
Repayments of Long-term Debt		(150,000)
Payments of Debt Issuance Costs		(547)
Redemption of senior secured notes	0	0
Cash (used in) provided by financing activities	(5,357)	39,151
Net (decrease) increase in cash and cash equivalents	(6,774)	73,424
Cash and cash equivalents, beginning of period	7,442	229
Cash and cash equivalents, end of period	$ 668	$ 73,653