Capital Stock (Details)						3 Months Ended						9 Months Ended		12 Months Ended
	Nov. 03, 2016 $ / shares	Apr. 28, 2015 $ / shares shares	Apr. 09, 2015 USD ($) $ / shares	Mar. 05, 2015 $ / shares	Dec. 31, 2012 $ / shares shares	Sep. 30, 2016 USD ($) $ / shares shares	Jun. 30, 2016 USD ($) $ / shares	Mar. 31, 2016 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares shares	Jun. 30, 2015 USD ($) $ / shares	Mar. 29, 2015 USD ($) $ / shares	Sep. 30, 2016 USD ($) $ / shares shares	Sep. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Feb. 24, 2016 USD ($)	Oct. 13, 2014 USD ($)
Class of Stock [Line Items]
Treasury stock (shares)						11,619,676						11,619,676		7,670,216
Preferred stock authorized (shares)						40,000,000						40,000,000		40,000,000
Preferred stock par value (usd per share) | $ / shares						$ 0.001						$ 0.001		$ 0.001
Common stock repurchases | $												$ 157,546,000
Cash dividends | $						$ 22,510,000	$ 22,959,000	$ 23,215,000	$ 23,620,000	$ 24,100,000	$ 0	$ 68,684,000	$ 47,720,000
Special Cash Dividend
Class of Stock [Line Items]
Dividends declared per common share (usd per share) | $ / shares				$ 6.73		$ 0.00			$ 0.00			$ 0.00	$ 6.73
Common stock dividends (usd per share) | $ / shares			$ 6.73
Cash dividends | $			$ 649,000,000
Regular Cash Dividend
Class of Stock [Line Items]
Dividends declared per common share (usd per share) | $ / shares						$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.00	$ 0.75	$ 0.50
Regular Cash Dividend | Subsequent Event
Class of Stock [Line Items]
Dividends declared per common share (usd per share) | $ / shares	$ 0.25
Warrant
Class of Stock [Line Items]
Warrants issued (shares)					16,789,972	159,243						159,243
Warrant, exercise price, per share (usd per share) | $ / shares					$ 0.001
Class A Common Stock
Class of Stock [Line Items]
Number of shares of common stock issued (shares)					78,754,269	100,384,850						100,384,850		100,015,546
Common stock, par value (usd per share) | $ / shares					$ 0.001	$ 0.001						$ 0.001		$ 0.001
Common stock, conversion ratio					1
Number of new shares issued from conversion (shares)													2,401,409
Number of shares called by each warrant (shares)					1
Number of warrants exercised (shares)						0			10,380			132,066	1,705,368
Number of shares received									10,380			132,066	1,705,361
Common stock, authorized (shares)						1,000,000,000						1,000,000,000		1,000,000,000
Shares sold (shares)		9,240,073
Shares issued (usd per share) | $ / shares		$ 56.00
Shares authorized (shares) | $															$ 400,000,000	$ 400,000,000
Treasury stock acquired (shares)						2,364,173						4,179,085		6,569,056
Common stock repurchases | $						$ 88,000,000						$ 158,000,000		$ 332,000,000
Share price (usd per share) | $ / shares						$ 37.35						$ 37.70		$ 50.59
Treasury stock acquired not yet settled (shares)						229,407								125,566
Treasury stock acquired, not yet settled | $						$ 8,000,000								$ 8,000,000
Treasury stock acquired life to date (shares)														7,670,216
Remaining authorized repurchase amount | $						$ 242,000,000						$ 242,000,000
Class B Common Stock
Class of Stock [Line Items]
Number of shares of common stock issued (shares)					4,455,767	5,605						5,605		5,605
Common stock, par value (usd per share) | $ / shares					$ 0.001	$ 0.001						$ 0.001		$ 0.001
Common stock, conversion ratio					1
Number of shares converted (shares)						0			0			0	2,401,409
Number of shares called by each warrant (shares)					1
Number of warrants exercised (shares)												0	0
Common stock, authorized (shares)						1,000,000,000						1,000,000,000		1,000,000,000
Preferred Stock
Class of Stock [Line Items]
Preferred stock authorized (shares)						40,000,000						40,000,000