CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Restricted Cash and Cash Equivalents, Current	$ 81,776	$ 133,597
Accounts receivable, allowance for doubtful accounts (in dollars)	5,644	3,246
Short-term restricted investments (in dollars)	227,795	277,556
Other current assets, restricted deposits (in dollars)	38,785	27,752
Long term restricted investments (in dollars)	$ 6,306	$ 3,826
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, Authorized shares	10,000	10,000
Preferred stock, Issued shares	0	0
Preferred stock, outstanding shares	0	0
Ordinary common stock in treasury, shares	28,476	26,648
Ordinary common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, Authorized shares	100,000	100,000
Common stock, Issued shares	51,993	51,340
Common stock, outstanding shares	23,517	24,692
Multi-Vote common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, Authorized shares	40,000	40,000
Common stock, Issued shares	0	0
Common stock, outstanding shares	0	0