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Consolidated Statements of Equity - USD ($) shares in Thousands | Total | Common Stock [Member] | Additional Paid-in Capital [Member] | Retained Earnings [Member] | Noncontrolling Interests [Member]
--- | --- | --- | --- | --- | ---
Balance at Dec. 31, 2014 | $ 2,265,566,000 | $ 960,000 | $ 886,877,000 | $ 1,376,782,000 | $ 947,000
Balance, Shares at Dec. 31, 2014 |  | 96,030 |  |  |
Net income (loss) | 335,691,000 |  |  | 336,320,000 | (629,000)
Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan | 20,128,000 | $ 5,000 | 20,123,000 |  |
Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan, shares |  | 463 |  |  |
Issuance of restricted stock and vesting of deferred stock |  | $ 5,000 | (5,000) |  |
Issuance of restricted stock and vesting of deferred stock, shares |  | 527 |  |  |
Issuance of restricted stock for acquisition consideration | 7,800,000 | $ 1,000 | 7,799,000 |  |
Issuance of restricted stock for acquisition consideration, shares |  | 114 |  |  |
Stock-based compensation expense | 32,129,000 |  | 32,129,000 |  |
Forfeitures of restricted stock, shares |  | (30) |  |  |
Repurchased common stock | (235,051,000) | $ (34,000) | (32,271,000) | (202,746,000) |
Repurchased common stock, shares |  | (3,365) |  |  |
Excess tax benefit related to employee stock incentive plans | 11,583,000 |  | 11,583,000 |  |
Balance at Dec. 31, 2015 | 2,437,846,000 | $ 937,000 | 926,235,000 | 1,510,356,000 | 318,000
Balance, Shares at Dec. 31, 2015 |  | 93,739 |  |  |
Net income (loss) | 324,596,000 |  |  | 324,914,000 | $ (318,000)
Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan | 22,022,000 | $ 5,000 | 22,017,000 |  |
Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan, shares |  | 473 |  |  |
Issuance of restricted stock |  | $ 5,000 | (5,000) |  |
Issuance of restricted stock, shares |  | 505 |  |  |
Stock-based compensation expense | 34,000,000 |  | 34,000,000 |  |
Forfeitures of restricted stock |  | $ (1,000) | 1,000 |  |
Forfeitures of restricted stock, shares |  | (53) |  |  |
Repurchased common stock | (61,828,000) | $ (9,000) | (12,075,000) | (49,744,000) |
Repurchased common stock, shares |  | (946) |  |  |
Excess tax benefit related to employee stock incentive plans | 4,131,000 |  | 4,131,000 |  |
Balance at Dec. 31, 2016 | 2,760,767,000 | $ 937,000 | 974,304,000 | 1,785,526,000 |
Balance, Shares at Dec. 31, 2016 |  | 93,718 |  |  |
Net income (loss) | 320,372,000 |  |  | 320,372,000 |
Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan | 23,276,000 | $ 5,000 | 23,271,000 |  |
Common stock issued under employee stock option, employee stock purchase plan and stock purchase plan, shares |  | 528 |  |  |
Issuance of restricted stock |  | $ 5,000 | (5,000) |  |
Issuance of restricted stock, shares |  | 536 |  |  |
Issuance of restricted stock for acquisition consideration | 2,658,000 | $ 1,000 | 2,657,000 |  |
Issuance of restricted stock for acquisition consideration, shares |  | 69 |  |  |
Stock-based compensation expense | 29,573,000 |  | 29,573,000 |  |
Forfeitures of restricted stock |  | $ (1,000) | 1,000 |  |
Forfeitures of restricted stock, shares |  | (92) |  |  |
Repurchased common stock | (70,192,000) | $ (10,000) | (12,473,000) | (57,709,000) |
Repurchased common stock, shares |  | (1,038) |  |  |
Excess tax benefit related to employee stock incentive plans | 0 |  |  |  |
Balance at Dec. 31, 2017 | $ 3,066,454,000 | $ 937,000 | $ 1,017,328,000 | $ 2,048,189,000 |
Balance, Shares at Dec. 31, 2017 |  | 93,721 |  |  |

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