Capital Stock, Stock Awards, and Stock Options (Narrative) (Details)		1 Months Ended	2 Months Ended	3 Months Ended		12 Months Ended
	Jul. 01, 2015 USD ($)	Jan. 31, 2017 $ / shares	Feb. 23, 2017 shares	Dec. 31, 2015 USD ($) employee $ / shares shares	Jun. 30, 2015 USD ($) employee shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Sep. 30, 2015 shares	May 14, 2015 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cost of shares repurchased by company | $						$ 108,948,000	$ 22,979,000	$ 327,718,000
Shares subject to award outstanding				81,475		67,225	81,475
Number of shares forfeited due to modification						4,175
Number of shares awarded in 2017						1,291
Exercised, Number of Shares						4,726
Number of shares granted						0
Stock options outstanding				191,722		186,996	191,722
Dividends declared per common share | $ / shares						$ 4.84	$ 9.10	$ 10.2
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares excluded from earnings per share						5,450	6,250	5,175
Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercised, Number of Shares						0	0	0
Number of shares granted						0	2,500	0
Stock options outstanding						0
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares excluded from earnings per share						102,000	102,000	52,000
Senior Manager [Member] | Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period							4 years
Maximum [Member] | Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						5 years
Minimum [Member] | Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						4 years
Education [Member] | Kaplan Stock Option and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense | $						$ 600,000	$ (1,800,000)	$ 900,000
Accrual balance related to stock based compensation | $						9,600,000
Stock compensation payouts | $				$ 0		$ 0	$ 0	0
Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion of Class A shares to Class B						0	10,822
Conversion of stock from Class A to Class B, percentage							1.00%
Class B Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Right to elect Board of Directors percentage						30.00%
Shares repurchased by company						229,498	46,226
Cost of shares repurchased by company | $						$ 108,900,000	$ 23,000,000
Number of shares authorized to be repurchased										500,000
Number of shares authorized to be repurchased remaining under previous authorization										159,219
Authorized shares remaining for repurchase						224,276
Market value of company's stock | $ / shares						$ 511.95
Class B Common Stock [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares affected by modification of terms				9,800
Number of employees affected by modification of terms of share awards | employee				1
Number of share awards with accelerated vesting				9,412
Number of shares forfeited due to modification				388
Share awards outstanding, restriction will lapse in 2017						28,200
Share awards outstanding, restriction will lapse in 2018						14,225
Share awards outstanding, restriction will lapse in 2019						24,550
Share awards outstanding, restriction will lapse in 2020						250
Stock-based compensation expense | $						$ 11,000,000	25,300,000	15,400,000
Total unrecognized compensation expense | $						$ 11,900,000
Years over which cost expected to be recognized						10 months 24 days
Class B Common Stock [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense | $						$ 2,400,000	$ 22,900,000	$ 2,700,000
Total unrecognized compensation expense | $						$ 8,200,000
Years over which cost expected to be recognized						4 years 2 months 12 days
Options outstanding exercisable now						114,872
Options outstanding exercisable in 2017						17,000
Options outstanding exercisable in 2018						17,000
Options outstanding exercisable in 2019						17,000
Options outstanding exercisable in 2020						17,000
Options outstanding exercisable in 2021						4,124
Intrinsic value of options outstanding | $						$ 15,900,000
Intrinsic value of options exercisable | $						15,900,000
Intrinsic value of options unvested | $						$ 0
Options unvested, shares				89,896		72,124	89,896
Options unvested, average exercise price | $ / shares				$ 755.65		$ 761.30	$ 755.65
Options unvested, weighted average remaining contractual term, years						8 years 1 month 6 days	9 years 1 month 6 days
Exercised, Number of Shares						4,726	40,527	19,125
Intrinsic value of options exercised | $						$ 1,200,000	$ 19,500,000	$ 6,700,000
Tax benefit from stock option exercises | $						$ 500,000	$ 7,800,000	$ 2,700,000
Number of shares granted						0
Weighted average fair value, granted options | $ / shares							$ 155.00	$ 178.95
Class B Common Stock [Member] | Employee Stock Option [Member] | Exercise Price Above Fair Market Value of Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted								50,000
Class B Common Stock [Member] | Subsequent Event [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares awarded in 2017			15,150
Class B Common Stock [Member] | Discontinued Operations [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation expense, net of forfeitures, due to modification | $				$ 6,000,000
Class B Common Stock [Member] | 2003 Employee Stock Option Plan [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for issuance						83,065
Shares reserved for stock awards granted under the plan						1,900,000
Class B Common Stock [Member] | 2003 Employee Stock Option Plan [Member] | Maximum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						10 years
Class B Common Stock [Member] | 2003 Employee Stock Option Plan [Member] | Minimum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						4 years
Class B Common Stock [Member] | 2012 Incentive Compensation Plan [Member] | Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Individual award limit authorization					50,000				77,258
Shares reserved for issuance						617,326
Shares reserved for stock awards granted under the plan					500,000				772,588
Shares subject to award outstanding						171,156
Shares available for future awards						446,170
Class B Common Stock [Member] | 2012 Incentive Compensation Plan [Member] | 2015 and 2014 Options Granted [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period							6 years	6 years
Class B Common Stock [Member] | 2012 Incentive Compensation Plan [Member] | Maximum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						10 years
Class B Common Stock [Member] | 2012 Incentive Compensation Plan [Member] | Minimum [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						4 years
Kaplan Restricted Stock [Member] | Senior Manager [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares subject to award outstanding						7,206
Kaplan Restricted Stock [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of company common stock | $ / shares		$ 1,327
Kaplan Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of company common stock | $ / shares							$ 1,180
Before Spin-off of Cable ONE [Member] | Class B Common Stock [Member] | Employee Stock Option [Member] | Exercise Price Above Fair Market Value of Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted								24,742
After Spin-Off of Cable ONE [Member] | Class B Common Stock [Member] | Employee Stock Option [Member] | Exercise Price Above Fair Market Value of Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted								77,258
Berkshire Exchange Transaction [Member] | Class B Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares repurchased by company								1,620,190
Cost of shares repurchased by company | $								$ 1,165,400,000
Cable Spin-Off [Member] | Class B Common Stock [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares affected by modification of terms					10,830
Number of share awards with accelerated vesting					6,324
Number of shares forfeited due to modification					4,506
Cable Spin-Off [Member] | Class B Common Stock [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation expense, net of forfeitures, due to modification | $	$ 23,500,000
Cable Spin-Off [Member] | Class B Common Stock [Member] | Discontinued Operations [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation expense, net of forfeitures, due to modification | $					$ 3,700,000
Cable Spin-Off [Member] | Class B Common Stock [Member] | Cable [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of employees affected by modification of terms of share awards | employee					21
Cable Spin-Off [Member] | July 2015 through December 2018 [Member] | Class B Common Stock [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation expense, net of forfeitures, due to modification | $	4,700,000
Cable Spin-Off [Member] | Q3 2015 [Member] | Class B Common Stock [Member] | Corporate Office [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation expense, net of forfeitures, due to modification | $	18,800,000
Cable Spin-Off [Member] | July 2015 through December 2018 [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental stock compensation expense, net of forfeitures, due to modification | $	$ 3,000,000