Stockholders' Equity (Narrative) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended				12 Months Ended				12 Months Ended				6 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 04, 2006	Dec. 31, 2012 Performance Shares Eligible To Be Earned [Member]	Dec. 31, 2012 Upside Case Achievement [Member]	Dec. 31, 2012 Upside Case Achievement [Member] Performance Shares Eligible To Be Earned [Member]	Dec. 31, 2012 Warrants [Member]	Dec. 31, 2012 Warrants [Member] Maximum [Member]	Dec. 31, 2012 Warrants [Member] Minimum [Member]	Dec. 31, 2012 Equity Incentive Plan [Member]	Jul. 13, 2012 Equity Incentive Plan [Member]	Jul. 13, 2012 Stock Appreciation Rights [Member]	Dec. 31, 2012 Stock Appreciation Rights [Member]	Dec. 31, 2011 Stock Appreciation Rights [Member]	Dec. 31, 2012 Common Stock [Member] Ratio	Jul. 13, 2012 Post-Split Basis [Member] Equity Incentive Plan [Member]	Jul. 13, 2012 Pre-Split Basis [Member] Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum percentage before exercise				20.00%
Number of shares authorized for issuance												7,500,000					18,600,000	9,300,000
Forward stock split of common stock																2
Shares of common stock available for issuance											1,900,000
Contractual life	Ten
Option vesting period	4 years
Dividend yield	$ 0
Total fair value of restricted stock units vested	$ 6.2	$ 2.4	$ 0.2
Term of performance share award	10 years
Performance shares eligible to be earned					83,332	83,332
Total fair market value of performance share awards that are vested during the period	$ 4,700,000
Performance share awards canceled during period							41,668
Fair value of stock appreciation rights	4.3
Weighted-average grant-date or remeasurement-date fair value per share													$ 32.94	$ 14.33	$ 14.91
Warrants to purchase aggregate shares of common stock								45,808
Weighted-average exercise price of options, per share								3.46
Warrants expiration date									2017	2014
Unrecognized stock-based compensation expense	$ 79.0
Unrecognized stock-based compensation expense, weighted-average period for recognition (years)	3 years 1 month 6 days