Stock-Based Compensation Expense (Narrative) (Detail)				12 Months Ended
	May 14, 2015 USD ($) shares	May 22, 2014 USD ($) shares	Jul. 08, 2011 USD ($) shares	Dec. 31, 2016 USD ($) Installment $ / shares shares	Dec. 31, 2015 USD ($) Installment $ / shares shares	Dec. 31, 2014 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period				4 years
Maximum contractual term				10 years
Stock-based compensation expense | $				$ 2,948,000	$ 21,033,000	$ 17,638,000
Tax benefits related to non-cash stock-based compensation awards | $				200,000	$ 8,400,000	$ 7,100,000
Unrecognized compensation expense | $				$ 2,800,000
Weighted average remaining life for recognition of unrecognized compensation expense				1 year 4 months 25 days
Non Employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value | $	$ 600,000	$ 600,000
President and Chief Executive Officer | Corporate Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated stock compensation costs | $				$ 8,700,000
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)				3,472,455	3,216,193
Options outstanding exercise price (USD per share) | $ / shares				$ 31.46	$ 34.88
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period				0	0
Equity Incentive Plan 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total awards of shares under equity incentive plan (in shares)			4,375,000
Options outstanding (in shares)				3,421,986
Options outstanding, unvested (in shares)				852,097
Options outstanding, vested (in shares)				2,569,889
Equity Incentive Plan 2011 | First and second anniversaries
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage				30.00%	30.00%
Equity Incentive Plan 2011 | Third and fourth anniversaries
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage				20.00%	20.00%
Equity Incentive Plan 2011 | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding exercise price (USD per share) | $ / shares				$ 1.34
Equity Incentive Plan 2011 | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding exercise price (USD per share) | $ / shares				$ 51.68
Equity Incentive Plan 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares)				50,469
Options outstanding exercise price range, lower limit (USD per share) | $ / shares				$ 20.32
Options outstanding exercise price range, upper limit (USD per share) | $ / shares				$ 26.40
Restricted Class Common Stock | Non Employee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	1 year	1 year
Shares of restricted Class A common stock (in shares)	30,365	11,664
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of restricted Class A common stock (in shares)				0
Grant date fair value | $				$ 600,000	$ 2,200,000
Shares of restricted Class A common stock (in shares)				400,000.0	600,000.0
Exercise price (USD per share) | $ / shares				$ 0.00
Total fair value of restricted stock awards vested | $				$ 0	$ 600,000
Restricted Stock | Officers and Members of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of annual award vesting installments | Installment				4	4
Aggregate voting power				50.00%
Restricted Stock | First and second anniversaries | Officers and Members of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of annual award vesting installments | Installment				2	2
Restricted Stock | Third and fourth anniversaries | Officers and Members of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of annual award vesting installments | Installment				2	2
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (USD per share) | $ / shares				$ 1.34	$ 3.84
Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (USD per share) | $ / shares				$ 24.00	$ 34.72
Equity Incentive Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock that remain authorized, reserved and available for issuance, not including shares underlying outstanding grants				30,000
Incentive Stock Options | Equity Incentive Plan 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of Class A common stock issued or transferred upon exercise of incentive stock options (in shares)			2,187,500
Restricted stock, Restricted Stock Units, Performance Shares, Performance Units and Other Awards | Equity Incentive Plan 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of Class A common stock issued as restricted stock, RSUs, performance shares, performance units and other awards (in shares)			1,500,000
Stock Appreciation Rights and Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earliest vesting period after grant date except in the event of retirement death or disability				3 years
Earliest vesting period after grant date if management objectives are achieved				1 year
Stock Appreciation Rights and Stock Options | Equity Incentive Plan 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value of stock options or SAR's available for grant to a participant (in shares)			1,437,500
Performance Based Compensation | Equity Incentive Plan 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value of stock options or SAR's available for grant to a participant (in shares)			375,000
Grant date fair value of stock options or SAR's available for grant to a participant (in shares) | $			$ 5,000,000
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Earliest vesting period after grant date except in the event of retirement death or disability				3 years
Earliest vesting period after grant date if management objectives are achieved				1 year