CONSOLIDATED STATEMENT OF SHAREHOLDERS' EQUITY - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Class A Common Stock	Paid-in Capital	Retained Earnings	Total
Balance at Dec. 31, 2014	$ 1,010	$ 2,215,479	$ 555,573	$ 2,772,062
Balance (in shares) at Dec. 31, 2014	102,392,208
Increase (Decrease) in Shareholders' Equity
Issuance of common stock upon exercise of options and vesting of restricted stock units		133		133
Issuance of common stock upon exercise of options and vesting of restricted stock units (in shares)	319,681
Stock-based compensation expense		7,724		7,724
Cash dividends (declared $0.08 per share)			(8,206)	(8,206)
Tax withholdings related to vesting of restricted stock units		(5,302)		(5,302)
Tax withholdings related to vesting of restricted stock units (in shares)	(130,934)
Net income			95,450	95,450
Balance at Jun. 30, 2015	$ 1,010	$ 2,218,034	$ 642,817	$ 2,861,861
Balance (in shares) at Jun. 30, 2015	102,580,955