"The Cadillac tax is a unique revenue generating mechanism that presumably targets excessively generous employer-sponsored health insurance packages, thereby increasing incentives for the prudent and efficient use of care. The tax is not intended to work at cross purposes with the general concept of employer-sponsored insurance, undermine the overall movement toward consumer directed care or hinder an employer's ability to offer cost effective strategies for improving the health and wellbeing of their workforce. The regulatory implementation of Section 4980I must serve these narrowly tailored objectives."