Restatement of Previously Issued Financial Statements - Effect of Restatement on Affected Line Items on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Feb. 28, 2013	Dec. 31, 2012
Condensed Consolidated Balance Sheet Data:
Deferred income taxes	$ 80,486	$ 68,324	$ 45,267
Total assets	778,487	806,851	767,578	$ 6,614
Other current liabilities	46,049	42,136	43,177	3,060
Total current liabilities	459,094	473,777	349,701
PEAKS Trust senior debt, excluding current portion	64,301	71,341	124,983
Total liabilities	661,756	691,205	637,892	$ 46,114
Retained earnings	941,024	940,449	970,405
Total shareholders' equity	116,731	115,646	129,686		$ 125,765
Total liabilities and shareholders' equity	778,487	$ 806,851	$ 767,578
As Previously Reported [Member]
Condensed Consolidated Balance Sheet Data:
Deferred income taxes	78,218
Total assets	776,219
Other current liabilities	46,233
Total current liabilities	459,278
PEAKS Trust senior debt, excluding current portion	58,442
Total liabilities	656,081
Retained earnings	944,431
Total shareholders' equity	120,138
Total liabilities and shareholders' equity	776,219
Interest Method Adjustment [Member]
Condensed Consolidated Balance Sheet Data:
Deferred income taxes	2,268
Total assets	2,268
Other current liabilities	(184)
Total current liabilities	(184)
PEAKS Trust senior debt, excluding current portion	5,859
Total liabilities	5,675
Retained earnings	(3,407)
Total shareholders' equity	(3,407)
Total liabilities and shareholders' equity	$ 2,268