Condensed Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash provided by (used in) operating activities	$ (40,715)	$ (126,388)
Cash flows from investing activities
Purchase of office facilities	(2,572)	(1,913)
Proceeds from sale of assets	43,252	0
Cash provided by (used in) investing activities	40,680	(1,913)
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	(2,947)	(3,023)
Repurchase of Class A non-voting common stock for cancellation	(3,798)	0
Tax deficiency from share-based awards	(747)	(270)
Other financing activities	51,700	118,100
Cash flow provided by (used in) financing activities	44,208	114,807
Net increase (decrease) in cash and cash equivalents	44,173	(13,494)
Cash and cash equivalents, beginning of period	63,364	63,807
Cash and cash equivalents, end of period	107,537	50,313
Class A Stock [Member]
Cash flows from financing activities
Repurchase of Class A non-voting common stock for cancellation	(3,798)
Parent Company [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash provided by (used in) operating activities	7,191	2,883
Cash flows from investing activities
Purchase of office facilities	0	0
Proceeds from sale of assets	0
Cash provided by (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	(2,947)	(3,023)
Tax deficiency from share-based awards	(747)	(270)
Other financing activities	0	0
Cash flow provided by (used in) financing activities	(7,492)	(3,293)
Net increase (decrease) in cash and cash equivalents	(301)	(410)
Cash and cash equivalents, beginning of period	907	439
Cash and cash equivalents, end of period	606
Parent Company [Member] \| Class A Stock [Member]
Cash flows from financing activities
Repurchase of Class A non-voting common stock for cancellation	(3,798)
Guarantor Subsidiaries [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash provided by (used in) operating activities	(2,061)	1,128
Cash flows from investing activities
Purchase of office facilities	0	0
Proceeds from sale of assets	0
Cash provided by (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
Tax deficiency from share-based awards	0	0
Other financing activities	0	0
Cash flow provided by (used in) financing activities	0	0
Net increase (decrease) in cash and cash equivalents	(2,061)	1,128
Cash and cash equivalents, beginning of period	2,586	1,557
Cash and cash equivalents, end of period	525
Guarantor Subsidiaries [Member] \| Class A Stock [Member]
Cash flows from financing activities
Repurchase of Class A non-voting common stock for cancellation	0
Non-Guarantor Subsidiaries [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash provided by (used in) operating activities	(45,845)	(130,399)
Cash flows from investing activities
Purchase of office facilities	(2,572)	(1,913)
Proceeds from sale of assets	43,252
Cash provided by (used in) investing activities	40,680	(1,913)
Cash flows from financing activities
Cash dividends paid on Class A non-voting and Class B voting common stock	0	0
Tax deficiency from share-based awards	0	0
Other financing activities	51,700	118,100
Cash flow provided by (used in) financing activities	51,700	118,100
Net increase (decrease) in cash and cash equivalents	46,535	(14,212)
Cash and cash equivalents, beginning of period	59,871	61,811
Cash and cash equivalents, end of period	106,406
Non-Guarantor Subsidiaries [Member] \| Class A Stock [Member]
Cash flows from financing activities
Repurchase of Class A non-voting common stock for cancellation	0
Consolidation, Eliminations [Member]
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Cash provided by (used in) operating activities	0	0
Cash flows from investing activities
Purchase of office facilities	0	0
Proceeds from sale of assets	0
Cash provided by (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
Tax deficiency from share-based awards	0	0
Other financing activities	0	0
Cash flow provided by (used in) financing activities	0	0
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	$ 0
Cash and cash equivalents, end of period	0
Consolidation, Eliminations [Member] \| Class A Stock [Member]
Cash flows from financing activities
Repurchase of Class A non-voting common stock for cancellation	$ 0

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