Condensed Consolidated Statement of Shareholders' Equity Dividend per share - USD ($)	Total	Common Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Additional Paid-in Capital [Member]
Common Stock, Shares, Outstanding	271,852,000
Common Stock, Value, Issued		$ 272,000
Additional Paid in Capital	$ 0
Retained Earnings (Accumulated Deficit)			$ 1,856,358,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	(11,354,000)			$ (11,354,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,845,276,000
Dividends	0.96
Net income	286,206,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	286,206,000
Other Comprehensive Income (Loss), Net of Tax	65,000			65,000
Shares of common stock repurchased		(3,484,000)
Treasury Stock, Value, Acquired, Par Value Method	(201,509,000)	$ 2,000	142,951,000		$ 58,556,000
Cumulative-effect adjustment for adoption of ASU 2016-02	(2,053,000)		(2,053,000)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		657,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	8,820,000				(17,566,000)
Adjustment to Retained Earnings ASU 2016-01	(17,566,000)
Stock Issued During Period, Shares, Other		316,000
Stock Issued During Period, Value, Stock Options Exercised	48,767,000				8,820,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition					48,767,000
APIC, Share-based Payment Arrangement, ESPP, Increase for Cost Recognition					18,535,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans		402,000
Stock Issued During Period, Value, Employee Stock Purchase Plan					18,535,000
Dividends, Common Stock, Cash	$ (260,032,000)		(260,032,000)
Common Stock, Shares, Outstanding	270,883,000
Common Stock, Value, Issued		$ 271,000
Additional Paid in Capital	$ 0
Retained Earnings (Accumulated Deficit)			1,793,012,000
Accumulated Other Comprehensive Income (Loss), Net of Tax				(11,997,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,781,286,000
Dividends	0.48
Net income	146,050,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	146,050,000
Other Comprehensive Income (Loss), Net of Tax	708,000			708,000
Shares of common stock repurchased		(1,862,000)
Treasury Stock, Value, Acquired, Par Value Method	(107,957,000)	$ 1,000	71,635,000		36,321,000
Cumulative-effect adjustment for adoption of ASU 2016-02	(89,000)		(89,000)
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		270,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	1,338,000				(7,623,000)
Adjustment to Retained Earnings ASU 2016-01	(7,623,000)
Stock Issued During Period, Shares, Other		50,000
Stock Issued During Period, Value, Stock Options Exercised	24,071,000				1,338,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition					24,071,000
APIC, Share-based Payment Arrangement, ESPP, Increase for Cost Recognition					18,535,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans		402,000
Stock Issued During Period, Value, Employee Stock Purchase Plan					18,535,000
Dividends, Common Stock, Cash	$ (129,810,000)		(129,810,000)
Common Stock, Shares, Outstanding	269,743,000
Common Stock, Value, Issued		$ 270,000
Additional Paid in Capital	$ 0
Retained Earnings (Accumulated Deficit)			1,737,528,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	11,289,000			(11,289,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 1,726,509,000
Common Stock, Shares, Outstanding	266,797,000
Common Stock, Value, Issued		$ 266,000
Additional Paid in Capital	$ 0
Retained Earnings (Accumulated Deficit)			1,671,786,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	(14,595,000)			(14,595,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,657,457,000
Dividends	0.48
Net income	353,459,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	353,459,000
Other Comprehensive Income (Loss), Net of Tax	327,000			327,000
Shares of common stock repurchased		(150,000)
Treasury Stock, Value, Acquired, Par Value Method	(9,201,000)		0		9,201,000
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		894,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	2,807,000				(35,984,000)
Adjustment to Retained Earnings ASU 2016-01	(35,984,000)
Stock Issued During Period, Shares, Other		100,000
Stock Issued During Period, Value, Stock Options Exercised	66,845,000				2,807,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition					66,845,000
APIC, Share-based Payment Arrangement, ESPP, Increase for Cost Recognition		$ 2,000			18,496,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans		391,000
Stock Issued During Period, Value, Employee Stock Purchase Plan					18,498,000
Dividends, Common Stock, Cash	$ (128,147,000)		(128,147,000)
Common Stock, Shares, Outstanding	267,304,000
Common Stock, Value, Issued		$ 267,000
Additional Paid in Capital	$ 12,194,000
Retained Earnings (Accumulated Deficit)			1,713,153,000
Accumulated Other Comprehensive Income (Loss), Net of Tax				(14,595,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,711,019,000
Dividends	0
Net income	183,945,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	183,945,000
Other Comprehensive Income (Loss), Net of Tax	327,000			327,000
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures		331,000
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	176,000				(18,966,000)
Adjustment to Retained Earnings ASU 2016-01	(18,966,000)
Stock Issued During Period, Shares, Other		6,000
Stock Issued During Period, Value, Stock Options Exercised	$ 31,063,000				176,000
APIC, Share-based Payment Arrangement, Increase for Cost Recognition		$ 1,000			31,063,000
APIC, Share-based Payment Arrangement, ESPP, Increase for Cost Recognition					18,496,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans		391,000
Stock Issued During Period, Value, Employee Stock Purchase Plan					$ 18,497,000
Common Stock, Shares, Outstanding	268,032,000
Common Stock, Value, Issued		$ 268,000
Additional Paid in Capital	$ 42,963,000
Retained Earnings (Accumulated Deficit)			$ 1,897,098,000
Accumulated Other Comprehensive Income (Loss), Net of Tax	(14,268,000)			$ (14,268,000)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 1,926,061,000